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La-Faujasite zeolite activated with boron trifluoride: synthesis and application as solid acid catalyst for isobutane–isobutene alkylation

La-Faujasite zeolite activated with boron trifluoride: synthesis and application as solid acid... The sodium form of Faujasite Y (Na-FAU) zeolite has been synthesized by the hydrothermal method, and it has been exchanged with ammonium sulphate and later with lanthanum (III) chloride solutions to obtain the La-FAU catalyst. The three zeolites Na-FAU, NH -FAU and La-FAU have been characterized by microcrystalline X-ray diffraction, X-ray fluo- rescence, surface area, pore volume and Brönsted acid sites. The La-FAU catalyst has been successfully activated with boron trifluoride etherate, and it has been tested in the alkylation reaction of isobutane with isobutene up to 112 h of time on stream, since the raw La-FAU catalyst showed a rapid deactivation. Keywords Faujasite · Lanthanum (III) · Alkylation · Isooctane Introduction contains eight cavities, each of diameter ≈  1.3  nm. The three-dimensional channels, which run parallel to [110], The alkylation reaction of isobutane with the C4 cut from have 12-ring windows with free apertures of about 0.74 nm. fluid catalytic cracking (FCC) or steam cracking (SC) allows The difference between zeolites X and Y is in their Si/Al to increase the amount and quality of the gasoline cut in oil ratios which are 1–1.5 and 1.5–3, respectively. refineries. This reaction is carried out in liquid phase at low Faujasite-type  zeolites  are one of the most important temperature and pressure, catalyzed by mineral acids like classes of zeolitic materials and are largely used in industrial hydrofluoric acid and sulfuric acid. This fact represents a processes such as FCC, isomerisation, alkylation and organ- serious drawback, not only due to the corrosive character of ics and air separations. Y-zeolite is important as catalyst for these acids, but also due to the high sulfuric acid consump- the industrial reactions in the petroleum refining and petro- tion and the tropism to form aerosols of hydrofluoric acid. chemistry such as cracking, hydrocracking, and isomeriza- Since many years ago, scientists have tried to replace these tion. The Si/Al ratio is enhanced by dealumination of NH -Y liquid acids with solid acids, typically zeolites, but the actual for their practical application at high-temperature reactions. fact is that a solid acid catalyst with the performance of the The resulting materials are hydrothermally more stable (the liquid acids remains still to be found [1–4]. so-called ultrastable Y zeolite, USY). The main component The  Faujasite-type zeolites all have the same frame- of fluid catalytic cracking (FCC) catalysts is rare earth-con- work structure, and they crystallize with cubic symmetry. taining USY zeolites. The general composition of the unit cell of Faujasite  is In this work, a catalyst based on zeolite Na-Faujasite has (Na ,Ca,Mg) [Al Si O]·240 H O. The unit cell been prepared by hydrothermal synthesis and ionic exchange 2 29 58 134 384 2 3+ with a La salt. This catalyst has been tested in the alkyla- tion reaction of isobutane (iC ) with isobutene (iC ), which 4 4 can be considered as a model of the industrial process, * Laureano Canoira laureano.canoira.lopez@upm.es since the main alkylation product, 2,2,4-trimethylpentane (2,2,4-TMP, isooctane, iC ) is the reference compound for 1 8 Environmental Studies Research Group GEA-UPM, ETS the octane rating of gasolines. The sodium form of the zeo- Ingenieros de Minas y Energía, Universidad Politécnica de lite Faujasite has been converted to the acid form by ionic Madrid, Ríos Rosas 21, 28003 Madrid, Spain Vol.:(0123456789) 1 3 354 Applied Petrochemical Research (2021) 11:353–362 exchange with lanthanum (III) chloride, since exchanging The feed of gases (isobutane, isobutene, synthetic air and with rare earth cations greatly improve the hydrothermal nitrogen) was controlled using mass flow controllers from 3+ stability of zeolites [5]. The hydrolysis of the La cations Brook Instrument BV, model 5850 TR, with a range 0–6 produced Brönsted acid sites, after Eqs. 1 and 2, where the NL/h and 1% accuracy. The back pressure regulator was negative charges of the zeolite framework are neutralized by also from Brook Instrument BV, model 5866, with a range hydroxylated lanthanum cations and protons: 0–2 bar (0–20 hPa) and 0.5% accuracy. The feed of liquids was done with a linear actuator from Sage Instruments, 3+ 2+ − − − + 3Y La H O → 2Y La (OH) + Y H , (1) model 341B, with a speed range from 0.022 to 0.321 m/h, and a flow range from 0.67 to 180 mL/h depending on the syringe size. All connections between these items of equip- 3+ − − + − + 3Y La H O → Y La (OH) + 2Y 2H . (2) 2 2 ment were done with ¼” SS tube using Hoke fittings and electro-valves from Hirschmann model 12B GDM. Pressure X-zeolite [6, 7], Y-zeolite [8–10] and HZSM-5 [11] zeo- measurements were carried out with a sensor DS-Europe, lite have been used previously for this alkylation reaction. model LP634, and temperature measurements were done Zeolite catalysts have been also tested for the etherification with type-K thermocouples from Sirsa SA. Figure 1 shows reaction of methanol or ethanol and isobutene, to produce a scheme of this pilot plant. Methyl tert-Butyl Ether (MTBE) and Ethyl tert-Butyl Ether X-ray diffraction analysis (XRD) of microcrystalline sol- (ETBE), respectively, well used octane boosters for gasoline ids were carried out in an instrument PANalytical PW1710 [12, 13]. Apart from its antiknock characteristics, alkylate with copper Kα radiation (λ = 0.154 nm) set at 40 kV and oil is also known for its clean burning characteristics due to 40 mA, scanning from 4° to 60° at 2°/min. the absence of sulphur, olefins, and aromatics. X-ray fluorescence analysis (XRF) were carried out in With the use of catalyst based on Faujasite zeolite for a wavelength dispersive instrument PANalytical PW1404 alkylation, the refinery could avoid the dangerous use of with Sc-Mo tube, using pearls of lithium tetraborate. For corrosive liquid acids, that could also leach some sulphur the analysis of lanthanum, pressed pellets have been used, to the fuel streams. The novelty of this work is the activa- since the pearls were elaborated with a tiny amount of lan- tion of a rapidly deactivated La-Faujasite catalyst with boron thanum oxide. trifluoride etherate, that allow maintain the catalyst activity Atomic absorption spectrophotometry analyses were car- for 112 h on stream. ried out in an instrument Philips PU9100X with a N O/C H 2 2 2 flame and selecting for B analysis the line with λ = 249.8 nm. Gas chromatography analysis (GC-FID) was carried out Experimental section in a chromatograph Agilent 5840 with FID detector, in the analytical conditions shown in Table 1. Equipment Thermogravimetric analysis (TGA) was carried out in an instrument TGA2 Mettler heating the sample from ambient The zeolite Na-Faujasite syntheses were carried out in a 1L temperature to 800 °C at a rate of 10 °C/min under a con- autoclave Büchiglasuster. The ionic exchange of the zeolite stant nitrogen flow. catalysts was carried out in a 1L stirred glass tank reactor with a heating jacket, controlled with a type-K thermocouple and a proportional integrative differential (PID) controller Materials from PID Eng model TC-10. The reactor used for the reaction experiments was a Neutral sodium silicate solution, with 27%w/w of SiO and stainless steel (SS) tubular reactor (47.5 cm length × 4.0 cm 8%w/w of N a O was bought from Panreac. Sodium alu- o.d.), heated by three independent heating jackets, which minate, ammonium sulphate and sodium hydroxide were were controlled by an adaptive predictive control software bought from Probus. Lanthanum (III) chloride was bought from SCAP [14]. This reactor was connected: upstream to from Merck. Boron trifluoride etherate and isooctane a stainless steel (SS) vaporizer (10.5 cm length × 5.0 cm were bought from Sigma-Aldrich. High purity isobutane o.d.) filled with glass Raschig rings, and downstream (> 99.9%) and isobutene (> 99.9%) were bought from Air consecutively to: (i) a SS heat exchanger (tube and shell, Liquide and they were used without further purification. 15.5 cm length × 5.0 cm o.d.) cooled by an ethylene gly- Table  2 summarizes the composition of the nuclea- col–water solution using a circulation pump from Electro tion and crystallization gels, for a total reaction volume of AD model H-5P3; (ii) a SS gas–liquid separator (15.5 cm 500 mL and 20%w/w of nucleation gel, and the amounts of length × 5.0  cm o.d.), and (iii) a SS liquid storing tank the above commercial reagents necessary to achieve these (10.5 cm length × 5.0 cm o.d.). compositions. 1 3 Applied Petrochemical Research (2021) 11:353–362 355 Fig. 1 Scheme of the pilot plant Table 1 GC-FID parameters Table 2 Reagents amounts for the synthesis of zeolite Na-Faujasite GC column Stainless steel, packed, 3 m × 0.3175 cm, Parameter Nucleation gel Crystallization gel Difference HP 10% UCV phase on Chromosorb AW SiO /Al O 3.444 10.00 – 80/100 mesh 2 2 3 Na O/SiO 1.463 0.505 – 2 2 Initial temperature, °C 40 H O/Na O 35.93 35.42 – 2 2 Initial time, min 3 SiO , mol 0.1056 1.5438 – Rate, °C/min 10 Al O , mol 0.0307 0.1543 – 2 3 Final temperature, °C 175 Na O, mol 0.1546 0.7842 – Final time, min 10 H O, mol 5.55 27.7 – Injector temperature, °C 200 Sodium silicate, g 23.47 343.5 320.05 FID temperature, °C 200 Sodium aluminate, g 5.035 25.32 20.285 He Flow, mL/min 7 Sodium hydrox- 7.72 15.60 7.89 Injection device Hamilton precision syringes, 100 µL/10 µL ide, g Distilled water, mL 84.75 276.71 191.96 Catalyst preparation aluminate was added, stirring the mixture until complete Formation of the nucleation gel dissolution of both reagents. Afterwards, the sodium sili- cate was slowly added, forming a gel which was stirred at In the autoclave, the sodium hydroxide was dissolved in 500 rpm during 1 h. This nucleation gel was left standing at room temperature for 48 h without any agitation. distilled water at room temperature, and later the sodium 1 3 356 Applied Petrochemical Research (2021) 11:353–362 Crystallization procedure Table 3 Chemical composition of zeolite catalysts by XRF %w/w Na-FAU NH -FAU La-FAU La-FAU One hour before the end of the nucleation gel aging, a new SiO 43.67 47.31 57.30 60.1 gel was prepared in exactly the same way as indicated for 2 Al O 18.37 20.00 25.30 25.8 the nucleation gel, but with the reagent amounts shown in 2 3 Na O 13.96 2.74 4.10 3.00 the Difference column of Table  2. This gel was stirred at 2 TiO 0.046 0.060 – – 500 rpm for 1 h. After aging, the nucleation gel was acti- 2 Fe O 0.076 0.076 – – vated heating it at 60 °C in a water bath, and it was mixed 2 3 La O – – 1.40 1.40 with the recently prepared additional gel at 60 °C under stir- 2 3 SiO /Al O 2.37 2.37 2.26 2.35 2 2 3 ring. This full crystallization gel was stirred at 500 rpm in Na O/SiO 3.13 17.26 13.84 20.03 the autoclave until the crystallization temperature of 100 °C 2 2 B – – – 2.6 was reached. Afterwards, the reaction mixture was kept at Si/Al molar ratio 2.02 2.01 1.93 1.98 100 °C without stirring during 4 h. Later, the reaction mix- Si/La molar ratio – – 111.17 116.6 ture was centrifuged at 1000 rpm, the mother liquid was LOI 22.10 19.80 11.30 7.1 discarded and the solid was washed with distilled water sev- Σ% 98.22 90.00 99.40 100.0 eral times, eliminating the washing water by filtration, until neutral pH was reached in the washing water. The white Analyzed by atomic absorption spectrophotometry after alkylation solid obtained was dried at 120 °C for 12 h. XRD and XRF experiments analyses showed that it consisted of the sodium form of Fau- Loss on ignition (LOI) jasite (Na-FAU). Composition of zeolite La-FAU catalyst after 112  h of time on stream (TOS) in alkylation experiments Preparation of the active zeolite Faujasite catalyst 4. The mineralogical composition of the catalysts and their The sodium form of zeolite Faujasite (Na-FAU) was con- verted to the catalytically active form by ionic exchange in crystallinity have been determined by XRD following the standard method ASTM D3906-03 (2013), as the average solution as follows: To prepare the zeolite catalyst, the sodium form of the ratio of X-ray counts of selected diffraction peaks in the samples and in a supposedly full crystalline Na-FAU zeolite zeolite Na-FAU was stirred at room temperature with a 5%w/v solution of ammonium sulphate during 24 h. The taken as reference. The BET surface and pore volume of the catalysts were solid was filtered and washed until absence of sulphate in the washing waters (checking by silver sulphate precipitation analyzed by nitrogen adsorption–desorption isotherms in a Micromeritics ASAP-2010 instrument and the results are with a diluted solution of silver nitrate). This ionic exchange procedure was repeated three times [4]. To obtain the zeolite summarized in Table 5. Prior to the measurements, all sam- ples were degassed at 300 °C under vacuum overnight. La-FAU catalyst, the NH -FAU zeolite was exchanged with a 0.5%w/v solution of lanthanum (III) chloride for 24 h at The acid site strength was investigated by temperature programmed ammonia desorption (NH -TPD) on an ASAP room temperature with stirring. The solid was filtered and washed with distilled water until absence of chlorides in the 2920 analyzer. Before the measurement, approximately 0.1 g dry samples were degassed under He flow at 500 °C for 1 h. washing waters (checking by silver chloride precipitation with a diluted solution of silver nitrate). The La-FAU zeo- After cooling to 120 °C, the sample was exposed to NH (10%v/v) − He gas flow for 30 min. Then, the sample was lite was dried at 120 °C, and calcined in an oven at 550 °C overnight, rising the oven temperature at 100 °C steps and swept by He for 1 h to remove the physically adsorbed NH , and the TPD was carried out from 120 to 600 °C using a keeping the La-FAU zeolite at each step for 1 h. The amount −1 of La-FAU zeolite was 39.66 g (6.0% yield based on crystal- heating rate of 10 °C  min . lization gel of Table 2, including water). The catalysts were prepared with the active form of the Alkylation reaction zeolite, and the fraction between 0.5 and 1.0 mm was used for the fixed-bed experiments [10]. The catalyst La-FAU was placed in the bottom section of the tubular reactor supported on rockwool and prior to Characterization each reaction it was activated in air at 538 °C during 2 h. Isobutane, isobutene and nitrogen as diluent were fed to XRD and XRF analyses were carried out on all samples the reactor in the mass flows required for each experiment, that lasted for about 8 h, at a weight hourly spatial velocity to ascertain the chemical and mineralogical composition of these catalysts, and they are summarized in Tables  3 and (WHSV) defined in Eq.  3: 1 3 Applied Petrochemical Research (2021) 11:353–362 357 Table 4 X-ray counts of zeolite a b c 2θ (°) Na-FAU Na-FAU NH -FAU La-FAU La-FAU La-FAU catalysts by XRD 15.3–15.9 327 281 133 53 36 – 18.5–18.9 109 100 78 27 18 – 20.1–20.7 178 156 103 35 24 – 23.7–24.1 328 344 192 67 41 – 26.6–27.6 215 220 129 32 20 86 30.3–31.3 108 83 44 8 – – 31.0–32.0 290 228 94 26 17 – 33.6–34.8 61 72 41 10 – – Σcounts 1616 1484 814 258 156 86 Mean 202 185.5 101.8 32.3 26 10.8 Crystall.,% 100.0 91.8 50.3 16.0 12.9 5.3 Na-FAU zeolite taken as reference Crystallinity of zeolite La-FAU catalyst after 56 h TOS Crystallinity of zeolite La-FAU catalyst after 112 h TOS Table 5 BET Surface, micropore volume and total acidity of the zeo- A iC8 Isooctane selectivity, Si = × 100, (5) lite catalysts C8 A + A iC8 others Sample Na-FAU NH -FAU La-FAU where A is the peak area of isooctane and A is the iC8 others S, m /g 498 497 489 BET peak area of other alkylation and isobutene oligomerization V, cm /g 0.207 0.206 0.202 micro products. Acidity, mmol NH /g 1.003 1.002 0.988 Results and discussion m + m iC4 iC4 WHSV = , (3) Catalyst characterization catalyst The chemical composition of zeolites prepared in this work where m was the mass flow of isobutene in g/h, m iC4 iC4 was analyzed by XRF and it is summarized in Table  3. was the mass flow of isobutane in g/h and m was the catalyst Faujasite-type zeolites with Si/Al ratio near one are usu- catalyst mass in g. ally denoted by X-zeolite, whereas, those with Si/Al ratio All experiment were carried out in vapor phase, and higher than two are usually denoted by Y-zeolite. The Si/ the reactor effluents were sampled with a 100 µL gas Al molar ratio for all zeolites in this study is around 2.0, syringe through a septum placed at the reactor outlet and which means that it could be possible that some of the alu- were immediately injected in the GC. A heating wire was minium atoms are extra-framework (EFAL), and they could installed at the reactor outlet to avoid condensation of any be exchanged to increase the acid strength of the catalyst. liquid products before sampling. After each experiment, The ion exchange procedures greatly decrease the crystal- the catalyst was purged with a nitrogen flow of 6 NL/h linity of the zeolites, thus the Na-FAU prepared in this work for 2 h at 500 °C to desorb all products occluded in the has almost the same crystallinity (92%) as the reference Na- zeolite channels. FAU, but the La-FAU retains only 16% crystallinity with The isobutene conversion (isobutene was always the respect to reference. Figures 2, 3, 4, 5, 6 show the diffrac - limiting reagent) was calculated from Eq. 4: tograms of the FAU zeolites, where the decrease of crystal- A − A isobut exp linity with time on stream is evident. However, the BET Isobutene conversion = × 100, (4) surface, the total micropore volume and the acidity results isobut remain practically unaffected by the ionic exchange, which where A represent the peak area of isobutene detected in isobut differs from previously reported results [8 ]. The BET surface the chromatogram when the reaction system is run without of this work catalyst (Table 5) is slightly higher than the any catalyst, and A represent this same peak area in each exp value of 470 m /g reported for other alkylation catalysts, and experiment with catalyst. the pore volume somewhat lower than the values between The 2,2,4-TMP selectivity was calculated from Eq. 5: 0.255 and 0.295 cm /g also reported [6]. 1 3 358 Applied Petrochemical Research (2021) 11:353–362 Fig. 2 DRX of Na-FAU Fig. 3 DRX of NH -FAU La‑FAU catalyst activation NL/h, iC flow 0.74 NL/h). This activated La-FAU cata- lyst showed an activity equal to the original catalysts, that The La-FAU catalysts showed a quick deactivation in the remained after 112  h TOS. In fact, the effect of boron could be due to the substitution of the extra-framework first alkylation experiments after a few minutes on stream [3]. Thus, it was activated by treatment with boron tri- (EFAL) aluminium atoms by boron atoms, since boron appears in the chemical analysis of the catalyst after all the fluoride etherate, injecting this solution (0.06 mL/min) with the isobutane/isobutene feed (molar ratio iC /iC alkylation reactions in 2.6%w/w, see Table 3. 4 4 −1 5.0, temperature 90  °C, WHSV 0.2  h , iC flow 3.70 1 3 Applied Petrochemical Research (2021) 11:353–362 359 Fig. 4 DRX of calcined La-FAU Fig. 5 DRX of La-FAU after 56 h TOS Fig. 6 DRX of La-FAU after 112 h TOS C fraction is composed of other trimethylpentanes apart Alkylation reaction from 2,2,4-TMP (2,3,3-TMP and 2,3,4-TMP), dimethyl- hexanes (DMH) (2,4-DMH, 2,5-DMH and 3,4-DMH), C This reaction of isobutane with isobutene was carried out olefins, and other C alkanes. Isooctane, iC , 2,2,4-TMP, is as a model reaction for the alkylation of isobutane with 8 8 the C hydrocarbon with the highest research octane num- the C cut from FCC, where isobutene is the most reac- ber (RON) and motor octane number (MON) of 100 points. tive component of this C fraction. The product analyzed These other C alkylation and higher molecular weight was 2,2,4-trimethylpentane (2,2,4-TMP, isooctane, iC ), products C have been quantified in the chromatograms, although obviously other branched C and higher molecular and their areas have been taken into account to calculate the weight compounds C are produced in this alkylation. The 1 3 360 Applied Petrochemical Research (2021) 11:353–362 isooctane selectivity after Eq. 5. The effect of reagents molar The isooctane selectivity reached the highest value of −1 ratio, temperature and WHSV on the isobutene conversion 15.1% at WHSV of 0.10  h , but with the lowest isobutene and isooctane selectivity has been studied. conversion of 48.1%. Thus, it could be estimated that the optimal reaction con- =  Eec ff t of the molar ratio isobutane/isobutene iC /iC ditions for this La-FAU catalyst are 130 °C, molar ratio iC / 4 4 4 = −1 iC 15 and WHSV of 0.10  h . The effect of the molar ratio iC /iC was investigated at Figure 10 shows the thermogram of the La-FAU catalyst 4 4 −1 90 ºC and WHSV 0.05  h , and it is summarized Fig. 7. after one of the alkylation experiments. This thermogram The isooctane selectivity remained practically constant, shows one sharp peak at 156 °C, which corresponds to the but the isobutene conversion reached a maximum of 65% desorption of the C products, isooctane among them, and between molar ratios 10 and 15, in good agreement with another much broader peak between 456 and 475 °C, that the molar ratio of 13 for this reaction on La-FAU catalyst, would represent the desorption of higher molecular weight recently reported by Yang et al. [8]. This high molar ratio of products, C . The adsorption behavior of these catalysts has isobutane to isobutene is necessary to minimize the isobu- been reported recently in the literature [15]. tene oligomerization reaction, although it means that a great The crystallinity of the La-FAU catalyst after 56 h TOS amount of isobutane need to be recycled to make the process was slightly lower (13%) than the that of the new catalyst economically acceptable. (16%), both referred to the Na-FAU taken as crystalline reference. However, after 112 h TOS, the crystallinity has Eec ff t of the temperature decreased to 5.3%, although the La-FAU mass loss of cata- lyst was negligeable. The ee ff ct of temperature was investigated at molar ratio iC / The mechanism of this alkylation reaction could be sche- = −1 iC of 15 and WHSV 0.05  h , in the range 70–150 °C, and matized in Fig. 11 [5]: the results are summarized in Fig. 8. The highest isooctane selectivity was achieved at 130 °C but at lower isobutene conversion, 50%. As it was expected, when increasing the conversion to 65% at 90 °C, the isooc- tane selectivity decreased. The optimal temperature found in our experiments maximizing the isooctane selectivity was 130 °C, in disagreement with previously reported results of 80 °C [6], which gave more importance to the butenes conversion. Eec ff t of the WHSV The effect of the WHSV was investigated at 130  °C and molar ratio iC /iC of 15, and the results are summarized 4 4 in Fig. 9. Fig. 8 Effect of the temperature Fig. 7 Effect of the molar ratio isobutane/isobutene iC /iC Fig. 9 Effect of the WHSV 4 4 1 3 Applied Petrochemical Research (2021) 11:353–362 361 Fig. 10 Thermogram of the La-FAU catalyst after one of the alkylation experiments Fig. 11 Mechanism of alkyla- tion of isobutane iC with isobutene iC on La-FAU catalyst (F represents zeolite framework) An isobutene iC molecule is adsorbed on the Brönsted molecule adsorbs and react with the adsorbed terc-butyl acid sites and one H adds to the double bond, giving an carbocation, giving an adsorbed iso-octyl carbocation. The = − adsorbed terc-butyl carbocation. A second isobutene iC hydride transfer H from an adsorbed isobutane molecule 1 3 362 Applied Petrochemical Research (2021) 11:353–362 catalysts. Russ J Appl Chem 93(10):1586–1595. https:// doi. org/ iC (present in great excess in the vapor phase) produces 10. 1134/ S1070 42722 010146 the isooctane final molecule that desorbs from the catalyst 4. Gerzeliev IM, Temnikova VA, Saitov ZA, Asylbaev DF, Baskh- surface, leaving an adsorbed terc-butyl carbocation coming anova MN (2020) Synthesis of a catalyst for isobutane/butyl- from the isobutane iC that repeats the mechanistic cycle. enes alkylation promising for industrial application. Pet Chem 60(10):1170–1175. https://doi. or g/10. 1134/ S0965 54412 01000 35 These preliminary alkylation results on La-FAU catalyst 5. Zhang H, Xu J, Tang H, Yang Z, Liu R, Zhang S (2019) show the feasibility of trying this catalyst in a pilot scale Isobutane/2-butene alkylation reaction catalyzed by Cu-modified plant, avoiding the use of dangerous liquid mineral acids and and rare earth X-type zeolite. Ind Eng Chem Res 58(22):9690– their environmental problems associated. 9700. https:// doi. org/ 10. 1021/ acs. iecr. 9b016 38 6. Gerzeliev IM, Temnikova VA, Baskhanova MN, Khusaimova DO, Maksimov AL (2019) Effect of the textural characteristics of zeo- lite catalysts on the main indicators of isobutane alkylation with Conclusions butylenes. Pet Chem 59(S1):S95–S100. https:// doi. org/ 10. 1134/ S0965 54411 91300 5X 7. Gerzeliev IM, Temnikova VA, Baskhanova MN, Maksimov AL La-FAU Catalyst has been synthesized by hydrothermal 3+ (2020) Alkylation of isobutane with butylenes on catalysts with method and ion exchange with La solutions, and it has various NaX zeolites in the CaLaHX form. Russ J Appl Chem been successfully checked in the alkylation reaction of 93(10):1578–1585. https:// doi. org/ 10. 1134/ S1070 42722 010134 isobutane with isobutene. The rapidly deactivated original 8. Yang Z, Zhang R, Dai F, Tang H, Liu R, Zhang S (2020) Effect of framework Si/Al ratios on the catalytic performance of isobutane La-FAU catalyst has been reactivated by co-injection of a alkylation over LaFAU zeolites. Energy Fuels 34(8):9426–9435. boron trifluoride etherate during an alkylation experiment, https:// doi. org/ 10. 1021/ acs. energ yfuels. 0c013 88 and this catalyst reactivation lasted for at least 112 h of time 9. Zhou S, Zhang C, Li Y, Shao B, Luo Y, Shu X (2020) A facile on stream. way to improve zeolite Y-based catalysts’ properties and perfor- mance in the isobutane–butene alkylation reaction. RSC Adv 10(49):29068–29076. https:// doi. org/ 10. 1039/ D0RA0 3762A Acknowledgements The authors wish to thank the European Union 10. Zhou S, Zhang C, Li Y, Luo Y, Shu X (2020) Effect of particle for the financial support through program EIT Raw Materials from size of Al2 O3 binders on acidity and isobutane-butene alkyla- Horizon 2020 (Project 18259, BioLeach: Innovative Biotreatment of tion performance of zeolite Y-based catalysts. Ind Eng Chem Res Raw Materials) and UPM student Javier Hernando for technical work. 59(13):5576–5582. https:// doi. org/ 10. 1021/ acs. iecr. 9b062 80 11. Tonutti LG, Decolatti HP, Querini CA, Dalla Costa BO (2020) Open Access This article is licensed under a Creative Commons Attri- Hierarchical H-ZSM-5 zeolite and sulfonic SBA-15: The proper- bution 4.0 International License, which permits use, sharing, adapta- ties of acidic H and behavior in acetylation and alkylation reac- tion, distribution and reproduction in any medium or format, as long tions. Microporous Mesoporous Mater 305:110284. https:// doi. as you give appropriate credit to the original author(s) and the source, org/ 10. 1016/j. micro meso. 2020. 110284 provide a link to the Creative Commons licence, and indicate if changes 12. Agulló F, Alcántara R, Canoira L, Fernández-Sánchez J-M, Nav- were made. The images or other third party material in this article are arro A, Neila JR (1998) Continuous flow preparation of methyl- included in the article's Creative Commons licence, unless indicated tert-butyl ether (MTBE) over ZSM-5 catalyst in fixed-bed and otherwise in a credit line to the material. If material is not included in fluidized-bed reactors. React Kinet Catal Lett 64(1):161–167. the article's Creative Commons licence and your intended use is not https:// doi. org/ 10. 1007/ BF024 75384 permitted by statutory regulation or exceeds the permitted use, you will 13. Alcántara IMR, Alcántara E, Canoira L, Franco MJ, Navarro need to obtain permission directly from the copyright holder. To view a A (2000) Gas-phase synthesis of ethyl tert-butyl ether (ETBE) copy of this licence, visit http://cr eativ ecommons. or g/licen ses/ b y/4.0/ . on ZSM-5 catalyst in continuous fixed-bed and fluidized-bed reactors. React Kinet Catal Lett 69:239–246. https:// doi. org/ 10. 1023/A: 10056 31313 062 14. Alcantara R, Canoira L, Conde R, Fernandez-Sanchez JM, Nav- References arro A (1994) Automation of a fixed-bed continuous-flow reactor. J Automat Chem 16(5):187–193 1. Corma A, Martínez A (1993) Chemistry, catalysts, and processes 15. Patrylak LK, Yakovenko AV (2021) Alkylation of isobutane with for isoparaffin-olefin alkylation: actual situation and future trends. butenes under microcatalytic conditions in pulse mode. Vopr Catal Rev 35(4):483–570. https:// doi. org/ 10. 1080/ 01614 94930 Khimii i Khimicheskoi Tekhnologii 1:55–61. https:// doi. org/ 10. 80139 16 32434/ 0321- 4095- 2021- 134-1- 55- 61 2. Akhmadova KK, Magomadova MK, Syrkin AM, Egutkin NL (2019) History, current state, and prospects for development Publisher's Note Springer Nature remains neutral with regard to of isobutane alkylation with olefins. Theor Found Chem Eng jurisdictional claims in published maps and institutional affiliations. 53(4):643–655. https:// doi. org/ 10. 1134/ S0040 57951 90400 92 3. Gerzeliev IM, Temnikova VA, Saitov ZA, Maximov AL (2020) Features of the isobutane alkylation with butylenes on zeolite 1 3 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Petrochemical Research Springer Journals

La-Faujasite zeolite activated with boron trifluoride: synthesis and application as solid acid catalyst for isobutane–isobutene alkylation

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2190-5525
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Abstract

The sodium form of Faujasite Y (Na-FAU) zeolite has been synthesized by the hydrothermal method, and it has been exchanged with ammonium sulphate and later with lanthanum (III) chloride solutions to obtain the La-FAU catalyst. The three zeolites Na-FAU, NH -FAU and La-FAU have been characterized by microcrystalline X-ray diffraction, X-ray fluo- rescence, surface area, pore volume and Brönsted acid sites. The La-FAU catalyst has been successfully activated with boron trifluoride etherate, and it has been tested in the alkylation reaction of isobutane with isobutene up to 112 h of time on stream, since the raw La-FAU catalyst showed a rapid deactivation. Keywords Faujasite · Lanthanum (III) · Alkylation · Isooctane Introduction contains eight cavities, each of diameter ≈  1.3  nm. The three-dimensional channels, which run parallel to [110], The alkylation reaction of isobutane with the C4 cut from have 12-ring windows with free apertures of about 0.74 nm. fluid catalytic cracking (FCC) or steam cracking (SC) allows The difference between zeolites X and Y is in their Si/Al to increase the amount and quality of the gasoline cut in oil ratios which are 1–1.5 and 1.5–3, respectively. refineries. This reaction is carried out in liquid phase at low Faujasite-type  zeolites  are one of the most important temperature and pressure, catalyzed by mineral acids like classes of zeolitic materials and are largely used in industrial hydrofluoric acid and sulfuric acid. This fact represents a processes such as FCC, isomerisation, alkylation and organ- serious drawback, not only due to the corrosive character of ics and air separations. Y-zeolite is important as catalyst for these acids, but also due to the high sulfuric acid consump- the industrial reactions in the petroleum refining and petro- tion and the tropism to form aerosols of hydrofluoric acid. chemistry such as cracking, hydrocracking, and isomeriza- Since many years ago, scientists have tried to replace these tion. The Si/Al ratio is enhanced by dealumination of NH -Y liquid acids with solid acids, typically zeolites, but the actual for their practical application at high-temperature reactions. fact is that a solid acid catalyst with the performance of the The resulting materials are hydrothermally more stable (the liquid acids remains still to be found [1–4]. so-called ultrastable Y zeolite, USY). The main component The  Faujasite-type zeolites all have the same frame- of fluid catalytic cracking (FCC) catalysts is rare earth-con- work structure, and they crystallize with cubic symmetry. taining USY zeolites. The general composition of the unit cell of Faujasite  is In this work, a catalyst based on zeolite Na-Faujasite has (Na ,Ca,Mg) [Al Si O]·240 H O. The unit cell been prepared by hydrothermal synthesis and ionic exchange 2 29 58 134 384 2 3+ with a La salt. This catalyst has been tested in the alkyla- tion reaction of isobutane (iC ) with isobutene (iC ), which 4 4 can be considered as a model of the industrial process, * Laureano Canoira laureano.canoira.lopez@upm.es since the main alkylation product, 2,2,4-trimethylpentane (2,2,4-TMP, isooctane, iC ) is the reference compound for 1 8 Environmental Studies Research Group GEA-UPM, ETS the octane rating of gasolines. The sodium form of the zeo- Ingenieros de Minas y Energía, Universidad Politécnica de lite Faujasite has been converted to the acid form by ionic Madrid, Ríos Rosas 21, 28003 Madrid, Spain Vol.:(0123456789) 1 3 354 Applied Petrochemical Research (2021) 11:353–362 exchange with lanthanum (III) chloride, since exchanging The feed of gases (isobutane, isobutene, synthetic air and with rare earth cations greatly improve the hydrothermal nitrogen) was controlled using mass flow controllers from 3+ stability of zeolites [5]. The hydrolysis of the La cations Brook Instrument BV, model 5850 TR, with a range 0–6 produced Brönsted acid sites, after Eqs. 1 and 2, where the NL/h and 1% accuracy. The back pressure regulator was negative charges of the zeolite framework are neutralized by also from Brook Instrument BV, model 5866, with a range hydroxylated lanthanum cations and protons: 0–2 bar (0–20 hPa) and 0.5% accuracy. The feed of liquids was done with a linear actuator from Sage Instruments, 3+ 2+ − − − + 3Y La H O → 2Y La (OH) + Y H , (1) model 341B, with a speed range from 0.022 to 0.321 m/h, and a flow range from 0.67 to 180 mL/h depending on the syringe size. All connections between these items of equip- 3+ − − + − + 3Y La H O → Y La (OH) + 2Y 2H . (2) 2 2 ment were done with ¼” SS tube using Hoke fittings and electro-valves from Hirschmann model 12B GDM. Pressure X-zeolite [6, 7], Y-zeolite [8–10] and HZSM-5 [11] zeo- measurements were carried out with a sensor DS-Europe, lite have been used previously for this alkylation reaction. model LP634, and temperature measurements were done Zeolite catalysts have been also tested for the etherification with type-K thermocouples from Sirsa SA. Figure 1 shows reaction of methanol or ethanol and isobutene, to produce a scheme of this pilot plant. Methyl tert-Butyl Ether (MTBE) and Ethyl tert-Butyl Ether X-ray diffraction analysis (XRD) of microcrystalline sol- (ETBE), respectively, well used octane boosters for gasoline ids were carried out in an instrument PANalytical PW1710 [12, 13]. Apart from its antiknock characteristics, alkylate with copper Kα radiation (λ = 0.154 nm) set at 40 kV and oil is also known for its clean burning characteristics due to 40 mA, scanning from 4° to 60° at 2°/min. the absence of sulphur, olefins, and aromatics. X-ray fluorescence analysis (XRF) were carried out in With the use of catalyst based on Faujasite zeolite for a wavelength dispersive instrument PANalytical PW1404 alkylation, the refinery could avoid the dangerous use of with Sc-Mo tube, using pearls of lithium tetraborate. For corrosive liquid acids, that could also leach some sulphur the analysis of lanthanum, pressed pellets have been used, to the fuel streams. The novelty of this work is the activa- since the pearls were elaborated with a tiny amount of lan- tion of a rapidly deactivated La-Faujasite catalyst with boron thanum oxide. trifluoride etherate, that allow maintain the catalyst activity Atomic absorption spectrophotometry analyses were car- for 112 h on stream. ried out in an instrument Philips PU9100X with a N O/C H 2 2 2 flame and selecting for B analysis the line with λ = 249.8 nm. Gas chromatography analysis (GC-FID) was carried out Experimental section in a chromatograph Agilent 5840 with FID detector, in the analytical conditions shown in Table 1. Equipment Thermogravimetric analysis (TGA) was carried out in an instrument TGA2 Mettler heating the sample from ambient The zeolite Na-Faujasite syntheses were carried out in a 1L temperature to 800 °C at a rate of 10 °C/min under a con- autoclave Büchiglasuster. The ionic exchange of the zeolite stant nitrogen flow. catalysts was carried out in a 1L stirred glass tank reactor with a heating jacket, controlled with a type-K thermocouple and a proportional integrative differential (PID) controller Materials from PID Eng model TC-10. The reactor used for the reaction experiments was a Neutral sodium silicate solution, with 27%w/w of SiO and stainless steel (SS) tubular reactor (47.5 cm length × 4.0 cm 8%w/w of N a O was bought from Panreac. Sodium alu- o.d.), heated by three independent heating jackets, which minate, ammonium sulphate and sodium hydroxide were were controlled by an adaptive predictive control software bought from Probus. Lanthanum (III) chloride was bought from SCAP [14]. This reactor was connected: upstream to from Merck. Boron trifluoride etherate and isooctane a stainless steel (SS) vaporizer (10.5 cm length × 5.0 cm were bought from Sigma-Aldrich. High purity isobutane o.d.) filled with glass Raschig rings, and downstream (> 99.9%) and isobutene (> 99.9%) were bought from Air consecutively to: (i) a SS heat exchanger (tube and shell, Liquide and they were used without further purification. 15.5 cm length × 5.0 cm o.d.) cooled by an ethylene gly- Table  2 summarizes the composition of the nuclea- col–water solution using a circulation pump from Electro tion and crystallization gels, for a total reaction volume of AD model H-5P3; (ii) a SS gas–liquid separator (15.5 cm 500 mL and 20%w/w of nucleation gel, and the amounts of length × 5.0  cm o.d.), and (iii) a SS liquid storing tank the above commercial reagents necessary to achieve these (10.5 cm length × 5.0 cm o.d.). compositions. 1 3 Applied Petrochemical Research (2021) 11:353–362 355 Fig. 1 Scheme of the pilot plant Table 1 GC-FID parameters Table 2 Reagents amounts for the synthesis of zeolite Na-Faujasite GC column Stainless steel, packed, 3 m × 0.3175 cm, Parameter Nucleation gel Crystallization gel Difference HP 10% UCV phase on Chromosorb AW SiO /Al O 3.444 10.00 – 80/100 mesh 2 2 3 Na O/SiO 1.463 0.505 – 2 2 Initial temperature, °C 40 H O/Na O 35.93 35.42 – 2 2 Initial time, min 3 SiO , mol 0.1056 1.5438 – Rate, °C/min 10 Al O , mol 0.0307 0.1543 – 2 3 Final temperature, °C 175 Na O, mol 0.1546 0.7842 – Final time, min 10 H O, mol 5.55 27.7 – Injector temperature, °C 200 Sodium silicate, g 23.47 343.5 320.05 FID temperature, °C 200 Sodium aluminate, g 5.035 25.32 20.285 He Flow, mL/min 7 Sodium hydrox- 7.72 15.60 7.89 Injection device Hamilton precision syringes, 100 µL/10 µL ide, g Distilled water, mL 84.75 276.71 191.96 Catalyst preparation aluminate was added, stirring the mixture until complete Formation of the nucleation gel dissolution of both reagents. Afterwards, the sodium sili- cate was slowly added, forming a gel which was stirred at In the autoclave, the sodium hydroxide was dissolved in 500 rpm during 1 h. This nucleation gel was left standing at room temperature for 48 h without any agitation. distilled water at room temperature, and later the sodium 1 3 356 Applied Petrochemical Research (2021) 11:353–362 Crystallization procedure Table 3 Chemical composition of zeolite catalysts by XRF %w/w Na-FAU NH -FAU La-FAU La-FAU One hour before the end of the nucleation gel aging, a new SiO 43.67 47.31 57.30 60.1 gel was prepared in exactly the same way as indicated for 2 Al O 18.37 20.00 25.30 25.8 the nucleation gel, but with the reagent amounts shown in 2 3 Na O 13.96 2.74 4.10 3.00 the Difference column of Table  2. This gel was stirred at 2 TiO 0.046 0.060 – – 500 rpm for 1 h. After aging, the nucleation gel was acti- 2 Fe O 0.076 0.076 – – vated heating it at 60 °C in a water bath, and it was mixed 2 3 La O – – 1.40 1.40 with the recently prepared additional gel at 60 °C under stir- 2 3 SiO /Al O 2.37 2.37 2.26 2.35 2 2 3 ring. This full crystallization gel was stirred at 500 rpm in Na O/SiO 3.13 17.26 13.84 20.03 the autoclave until the crystallization temperature of 100 °C 2 2 B – – – 2.6 was reached. Afterwards, the reaction mixture was kept at Si/Al molar ratio 2.02 2.01 1.93 1.98 100 °C without stirring during 4 h. Later, the reaction mix- Si/La molar ratio – – 111.17 116.6 ture was centrifuged at 1000 rpm, the mother liquid was LOI 22.10 19.80 11.30 7.1 discarded and the solid was washed with distilled water sev- Σ% 98.22 90.00 99.40 100.0 eral times, eliminating the washing water by filtration, until neutral pH was reached in the washing water. The white Analyzed by atomic absorption spectrophotometry after alkylation solid obtained was dried at 120 °C for 12 h. XRD and XRF experiments analyses showed that it consisted of the sodium form of Fau- Loss on ignition (LOI) jasite (Na-FAU). Composition of zeolite La-FAU catalyst after 112  h of time on stream (TOS) in alkylation experiments Preparation of the active zeolite Faujasite catalyst 4. The mineralogical composition of the catalysts and their The sodium form of zeolite Faujasite (Na-FAU) was con- verted to the catalytically active form by ionic exchange in crystallinity have been determined by XRD following the standard method ASTM D3906-03 (2013), as the average solution as follows: To prepare the zeolite catalyst, the sodium form of the ratio of X-ray counts of selected diffraction peaks in the samples and in a supposedly full crystalline Na-FAU zeolite zeolite Na-FAU was stirred at room temperature with a 5%w/v solution of ammonium sulphate during 24 h. The taken as reference. The BET surface and pore volume of the catalysts were solid was filtered and washed until absence of sulphate in the washing waters (checking by silver sulphate precipitation analyzed by nitrogen adsorption–desorption isotherms in a Micromeritics ASAP-2010 instrument and the results are with a diluted solution of silver nitrate). This ionic exchange procedure was repeated three times [4]. To obtain the zeolite summarized in Table 5. Prior to the measurements, all sam- ples were degassed at 300 °C under vacuum overnight. La-FAU catalyst, the NH -FAU zeolite was exchanged with a 0.5%w/v solution of lanthanum (III) chloride for 24 h at The acid site strength was investigated by temperature programmed ammonia desorption (NH -TPD) on an ASAP room temperature with stirring. The solid was filtered and washed with distilled water until absence of chlorides in the 2920 analyzer. Before the measurement, approximately 0.1 g dry samples were degassed under He flow at 500 °C for 1 h. washing waters (checking by silver chloride precipitation with a diluted solution of silver nitrate). The La-FAU zeo- After cooling to 120 °C, the sample was exposed to NH (10%v/v) − He gas flow for 30 min. Then, the sample was lite was dried at 120 °C, and calcined in an oven at 550 °C overnight, rising the oven temperature at 100 °C steps and swept by He for 1 h to remove the physically adsorbed NH , and the TPD was carried out from 120 to 600 °C using a keeping the La-FAU zeolite at each step for 1 h. The amount −1 of La-FAU zeolite was 39.66 g (6.0% yield based on crystal- heating rate of 10 °C  min . lization gel of Table 2, including water). The catalysts were prepared with the active form of the Alkylation reaction zeolite, and the fraction between 0.5 and 1.0 mm was used for the fixed-bed experiments [10]. The catalyst La-FAU was placed in the bottom section of the tubular reactor supported on rockwool and prior to Characterization each reaction it was activated in air at 538 °C during 2 h. Isobutane, isobutene and nitrogen as diluent were fed to XRD and XRF analyses were carried out on all samples the reactor in the mass flows required for each experiment, that lasted for about 8 h, at a weight hourly spatial velocity to ascertain the chemical and mineralogical composition of these catalysts, and they are summarized in Tables  3 and (WHSV) defined in Eq.  3: 1 3 Applied Petrochemical Research (2021) 11:353–362 357 Table 4 X-ray counts of zeolite a b c 2θ (°) Na-FAU Na-FAU NH -FAU La-FAU La-FAU La-FAU catalysts by XRD 15.3–15.9 327 281 133 53 36 – 18.5–18.9 109 100 78 27 18 – 20.1–20.7 178 156 103 35 24 – 23.7–24.1 328 344 192 67 41 – 26.6–27.6 215 220 129 32 20 86 30.3–31.3 108 83 44 8 – – 31.0–32.0 290 228 94 26 17 – 33.6–34.8 61 72 41 10 – – Σcounts 1616 1484 814 258 156 86 Mean 202 185.5 101.8 32.3 26 10.8 Crystall.,% 100.0 91.8 50.3 16.0 12.9 5.3 Na-FAU zeolite taken as reference Crystallinity of zeolite La-FAU catalyst after 56 h TOS Crystallinity of zeolite La-FAU catalyst after 112 h TOS Table 5 BET Surface, micropore volume and total acidity of the zeo- A iC8 Isooctane selectivity, Si = × 100, (5) lite catalysts C8 A + A iC8 others Sample Na-FAU NH -FAU La-FAU where A is the peak area of isooctane and A is the iC8 others S, m /g 498 497 489 BET peak area of other alkylation and isobutene oligomerization V, cm /g 0.207 0.206 0.202 micro products. Acidity, mmol NH /g 1.003 1.002 0.988 Results and discussion m + m iC4 iC4 WHSV = , (3) Catalyst characterization catalyst The chemical composition of zeolites prepared in this work where m was the mass flow of isobutene in g/h, m iC4 iC4 was analyzed by XRF and it is summarized in Table  3. was the mass flow of isobutane in g/h and m was the catalyst Faujasite-type zeolites with Si/Al ratio near one are usu- catalyst mass in g. ally denoted by X-zeolite, whereas, those with Si/Al ratio All experiment were carried out in vapor phase, and higher than two are usually denoted by Y-zeolite. The Si/ the reactor effluents were sampled with a 100 µL gas Al molar ratio for all zeolites in this study is around 2.0, syringe through a septum placed at the reactor outlet and which means that it could be possible that some of the alu- were immediately injected in the GC. A heating wire was minium atoms are extra-framework (EFAL), and they could installed at the reactor outlet to avoid condensation of any be exchanged to increase the acid strength of the catalyst. liquid products before sampling. After each experiment, The ion exchange procedures greatly decrease the crystal- the catalyst was purged with a nitrogen flow of 6 NL/h linity of the zeolites, thus the Na-FAU prepared in this work for 2 h at 500 °C to desorb all products occluded in the has almost the same crystallinity (92%) as the reference Na- zeolite channels. FAU, but the La-FAU retains only 16% crystallinity with The isobutene conversion (isobutene was always the respect to reference. Figures 2, 3, 4, 5, 6 show the diffrac - limiting reagent) was calculated from Eq. 4: tograms of the FAU zeolites, where the decrease of crystal- A − A isobut exp linity with time on stream is evident. However, the BET Isobutene conversion = × 100, (4) surface, the total micropore volume and the acidity results isobut remain practically unaffected by the ionic exchange, which where A represent the peak area of isobutene detected in isobut differs from previously reported results [8 ]. The BET surface the chromatogram when the reaction system is run without of this work catalyst (Table 5) is slightly higher than the any catalyst, and A represent this same peak area in each exp value of 470 m /g reported for other alkylation catalysts, and experiment with catalyst. the pore volume somewhat lower than the values between The 2,2,4-TMP selectivity was calculated from Eq. 5: 0.255 and 0.295 cm /g also reported [6]. 1 3 358 Applied Petrochemical Research (2021) 11:353–362 Fig. 2 DRX of Na-FAU Fig. 3 DRX of NH -FAU La‑FAU catalyst activation NL/h, iC flow 0.74 NL/h). This activated La-FAU cata- lyst showed an activity equal to the original catalysts, that The La-FAU catalysts showed a quick deactivation in the remained after 112  h TOS. In fact, the effect of boron could be due to the substitution of the extra-framework first alkylation experiments after a few minutes on stream [3]. Thus, it was activated by treatment with boron tri- (EFAL) aluminium atoms by boron atoms, since boron appears in the chemical analysis of the catalyst after all the fluoride etherate, injecting this solution (0.06 mL/min) with the isobutane/isobutene feed (molar ratio iC /iC alkylation reactions in 2.6%w/w, see Table 3. 4 4 −1 5.0, temperature 90  °C, WHSV 0.2  h , iC flow 3.70 1 3 Applied Petrochemical Research (2021) 11:353–362 359 Fig. 4 DRX of calcined La-FAU Fig. 5 DRX of La-FAU after 56 h TOS Fig. 6 DRX of La-FAU after 112 h TOS C fraction is composed of other trimethylpentanes apart Alkylation reaction from 2,2,4-TMP (2,3,3-TMP and 2,3,4-TMP), dimethyl- hexanes (DMH) (2,4-DMH, 2,5-DMH and 3,4-DMH), C This reaction of isobutane with isobutene was carried out olefins, and other C alkanes. Isooctane, iC , 2,2,4-TMP, is as a model reaction for the alkylation of isobutane with 8 8 the C hydrocarbon with the highest research octane num- the C cut from FCC, where isobutene is the most reac- ber (RON) and motor octane number (MON) of 100 points. tive component of this C fraction. The product analyzed These other C alkylation and higher molecular weight was 2,2,4-trimethylpentane (2,2,4-TMP, isooctane, iC ), products C have been quantified in the chromatograms, although obviously other branched C and higher molecular and their areas have been taken into account to calculate the weight compounds C are produced in this alkylation. The 1 3 360 Applied Petrochemical Research (2021) 11:353–362 isooctane selectivity after Eq. 5. The effect of reagents molar The isooctane selectivity reached the highest value of −1 ratio, temperature and WHSV on the isobutene conversion 15.1% at WHSV of 0.10  h , but with the lowest isobutene and isooctane selectivity has been studied. conversion of 48.1%. Thus, it could be estimated that the optimal reaction con- =  Eec ff t of the molar ratio isobutane/isobutene iC /iC ditions for this La-FAU catalyst are 130 °C, molar ratio iC / 4 4 4 = −1 iC 15 and WHSV of 0.10  h . The effect of the molar ratio iC /iC was investigated at Figure 10 shows the thermogram of the La-FAU catalyst 4 4 −1 90 ºC and WHSV 0.05  h , and it is summarized Fig. 7. after one of the alkylation experiments. This thermogram The isooctane selectivity remained practically constant, shows one sharp peak at 156 °C, which corresponds to the but the isobutene conversion reached a maximum of 65% desorption of the C products, isooctane among them, and between molar ratios 10 and 15, in good agreement with another much broader peak between 456 and 475 °C, that the molar ratio of 13 for this reaction on La-FAU catalyst, would represent the desorption of higher molecular weight recently reported by Yang et al. [8]. This high molar ratio of products, C . The adsorption behavior of these catalysts has isobutane to isobutene is necessary to minimize the isobu- been reported recently in the literature [15]. tene oligomerization reaction, although it means that a great The crystallinity of the La-FAU catalyst after 56 h TOS amount of isobutane need to be recycled to make the process was slightly lower (13%) than the that of the new catalyst economically acceptable. (16%), both referred to the Na-FAU taken as crystalline reference. However, after 112 h TOS, the crystallinity has Eec ff t of the temperature decreased to 5.3%, although the La-FAU mass loss of cata- lyst was negligeable. The ee ff ct of temperature was investigated at molar ratio iC / The mechanism of this alkylation reaction could be sche- = −1 iC of 15 and WHSV 0.05  h , in the range 70–150 °C, and matized in Fig. 11 [5]: the results are summarized in Fig. 8. The highest isooctane selectivity was achieved at 130 °C but at lower isobutene conversion, 50%. As it was expected, when increasing the conversion to 65% at 90 °C, the isooc- tane selectivity decreased. The optimal temperature found in our experiments maximizing the isooctane selectivity was 130 °C, in disagreement with previously reported results of 80 °C [6], which gave more importance to the butenes conversion. Eec ff t of the WHSV The effect of the WHSV was investigated at 130  °C and molar ratio iC /iC of 15, and the results are summarized 4 4 in Fig. 9. Fig. 8 Effect of the temperature Fig. 7 Effect of the molar ratio isobutane/isobutene iC /iC Fig. 9 Effect of the WHSV 4 4 1 3 Applied Petrochemical Research (2021) 11:353–362 361 Fig. 10 Thermogram of the La-FAU catalyst after one of the alkylation experiments Fig. 11 Mechanism of alkyla- tion of isobutane iC with isobutene iC on La-FAU catalyst (F represents zeolite framework) An isobutene iC molecule is adsorbed on the Brönsted molecule adsorbs and react with the adsorbed terc-butyl acid sites and one H adds to the double bond, giving an carbocation, giving an adsorbed iso-octyl carbocation. The = − adsorbed terc-butyl carbocation. A second isobutene iC hydride transfer H from an adsorbed isobutane molecule 1 3 362 Applied Petrochemical Research (2021) 11:353–362 catalysts. Russ J Appl Chem 93(10):1586–1595. https:// doi. org/ iC (present in great excess in the vapor phase) produces 10. 1134/ S1070 42722 010146 the isooctane final molecule that desorbs from the catalyst 4. Gerzeliev IM, Temnikova VA, Saitov ZA, Asylbaev DF, Baskh- surface, leaving an adsorbed terc-butyl carbocation coming anova MN (2020) Synthesis of a catalyst for isobutane/butyl- from the isobutane iC that repeats the mechanistic cycle. enes alkylation promising for industrial application. Pet Chem 60(10):1170–1175. https://doi. or g/10. 1134/ S0965 54412 01000 35 These preliminary alkylation results on La-FAU catalyst 5. Zhang H, Xu J, Tang H, Yang Z, Liu R, Zhang S (2019) show the feasibility of trying this catalyst in a pilot scale Isobutane/2-butene alkylation reaction catalyzed by Cu-modified plant, avoiding the use of dangerous liquid mineral acids and and rare earth X-type zeolite. Ind Eng Chem Res 58(22):9690– their environmental problems associated. 9700. https:// doi. org/ 10. 1021/ acs. iecr. 9b016 38 6. Gerzeliev IM, Temnikova VA, Baskhanova MN, Khusaimova DO, Maksimov AL (2019) Effect of the textural characteristics of zeo- lite catalysts on the main indicators of isobutane alkylation with Conclusions butylenes. Pet Chem 59(S1):S95–S100. https:// doi. org/ 10. 1134/ S0965 54411 91300 5X 7. Gerzeliev IM, Temnikova VA, Baskhanova MN, Maksimov AL La-FAU Catalyst has been synthesized by hydrothermal 3+ (2020) Alkylation of isobutane with butylenes on catalysts with method and ion exchange with La solutions, and it has various NaX zeolites in the CaLaHX form. Russ J Appl Chem been successfully checked in the alkylation reaction of 93(10):1578–1585. https:// doi. org/ 10. 1134/ S1070 42722 010134 isobutane with isobutene. The rapidly deactivated original 8. Yang Z, Zhang R, Dai F, Tang H, Liu R, Zhang S (2020) Effect of framework Si/Al ratios on the catalytic performance of isobutane La-FAU catalyst has been reactivated by co-injection of a alkylation over LaFAU zeolites. Energy Fuels 34(8):9426–9435. boron trifluoride etherate during an alkylation experiment, https:// doi. org/ 10. 1021/ acs. energ yfuels. 0c013 88 and this catalyst reactivation lasted for at least 112 h of time 9. Zhou S, Zhang C, Li Y, Shao B, Luo Y, Shu X (2020) A facile on stream. way to improve zeolite Y-based catalysts’ properties and perfor- mance in the isobutane–butene alkylation reaction. RSC Adv 10(49):29068–29076. https:// doi. org/ 10. 1039/ D0RA0 3762A Acknowledgements The authors wish to thank the European Union 10. Zhou S, Zhang C, Li Y, Luo Y, Shu X (2020) Effect of particle for the financial support through program EIT Raw Materials from size of Al2 O3 binders on acidity and isobutane-butene alkyla- Horizon 2020 (Project 18259, BioLeach: Innovative Biotreatment of tion performance of zeolite Y-based catalysts. Ind Eng Chem Res Raw Materials) and UPM student Javier Hernando for technical work. 59(13):5576–5582. https:// doi. org/ 10. 1021/ acs. iecr. 9b062 80 11. Tonutti LG, Decolatti HP, Querini CA, Dalla Costa BO (2020) Open Access This article is licensed under a Creative Commons Attri- Hierarchical H-ZSM-5 zeolite and sulfonic SBA-15: The proper- bution 4.0 International License, which permits use, sharing, adapta- ties of acidic H and behavior in acetylation and alkylation reac- tion, distribution and reproduction in any medium or format, as long tions. Microporous Mesoporous Mater 305:110284. https:// doi. as you give appropriate credit to the original author(s) and the source, org/ 10. 1016/j. micro meso. 2020. 110284 provide a link to the Creative Commons licence, and indicate if changes 12. Agulló F, Alcántara R, Canoira L, Fernández-Sánchez J-M, Nav- were made. The images or other third party material in this article are arro A, Neila JR (1998) Continuous flow preparation of methyl- included in the article's Creative Commons licence, unless indicated tert-butyl ether (MTBE) over ZSM-5 catalyst in fixed-bed and otherwise in a credit line to the material. If material is not included in fluidized-bed reactors. React Kinet Catal Lett 64(1):161–167. the article's Creative Commons licence and your intended use is not https:// doi. org/ 10. 1007/ BF024 75384 permitted by statutory regulation or exceeds the permitted use, you will 13. Alcántara IMR, Alcántara E, Canoira L, Franco MJ, Navarro need to obtain permission directly from the copyright holder. To view a A (2000) Gas-phase synthesis of ethyl tert-butyl ether (ETBE) copy of this licence, visit http://cr eativ ecommons. or g/licen ses/ b y/4.0/ . on ZSM-5 catalyst in continuous fixed-bed and fluidized-bed reactors. React Kinet Catal Lett 69:239–246. https:// doi. org/ 10. 1023/A: 10056 31313 062 14. Alcantara R, Canoira L, Conde R, Fernandez-Sanchez JM, Nav- References arro A (1994) Automation of a fixed-bed continuous-flow reactor. J Automat Chem 16(5):187–193 1. Corma A, Martínez A (1993) Chemistry, catalysts, and processes 15. Patrylak LK, Yakovenko AV (2021) Alkylation of isobutane with for isoparaffin-olefin alkylation: actual situation and future trends. butenes under microcatalytic conditions in pulse mode. Vopr Catal Rev 35(4):483–570. https:// doi. org/ 10. 1080/ 01614 94930 Khimii i Khimicheskoi Tekhnologii 1:55–61. https:// doi. org/ 10. 80139 16 32434/ 0321- 4095- 2021- 134-1- 55- 61 2. Akhmadova KK, Magomadova MK, Syrkin AM, Egutkin NL (2019) History, current state, and prospects for development Publisher's Note Springer Nature remains neutral with regard to of isobutane alkylation with olefins. Theor Found Chem Eng jurisdictional claims in published maps and institutional affiliations. 53(4):643–655. https:// doi. org/ 10. 1134/ S0040 57951 90400 92 3. Gerzeliev IM, Temnikova VA, Saitov ZA, Maximov AL (2020) Features of the isobutane alkylation with butylenes on zeolite 1 3

Journal

Applied Petrochemical ResearchSpringer Journals

Published: Dec 1, 2021

Keywords: Faujasite; Lanthanum (III); Alkylation; Isooctane

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