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Catalytic Properties of Zeolites and Synthesized Superacid Systems During the Transformation of Model Reactions of Pentanes

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Catalytic Properties of Zeolites and Synthesized Superacid Systems During the Transformation of Model Reactions of Pentanes Advances in Engineering Research, volume 177 International Symposium on Engineering and Earth Sciences (ISEES 2018) Catalytic Properties of Zeolites and Synthesized Superacid Systems During the Transformation of Model Reactions of Pentanes Turlov s RA-B. Magomadova Marem .Kh. Heat Engineering and Hydraulics Department of Heat Engineering and Hydraulics Department of Grozny State Oil Technical University Grozny State Oil Technical University g . Grozny, Russia Grozny, Russia e - mail: [email protected] e - mail: [email protected] Madaeva A. D. Idrisova E.U. Heat Engineering and Hydraulics Department Heat Engineering and Hydraulics Department of Grozny State Oil Technical University of Grozny State Oil Technical University Grozny, Russia Grozny, Russia e - mail: ANITA [email protected] e - mail: idrisova999@mail ru Magomadova Madina. Kh. "Chemical technology of oil and gas Department of Grozny State Oil Technical University Grozny, Russia e - mail : [email protected] Abstract—Investigation of the catalytic activity and selectivity II. THE METHODOLOGY OF THE EXPERIMENT of the obtained products of various nature and composition of Before conducting the experiment, the test samples of catalysts in the course of model catalytic reactions, cracking, catalysts (zeolites, AAS and γ-Al2O3) with a fractional isomerization, disproportionation. The study of the acid sites of composition of 0.25 ÷ 40.5 mm were loaded into a quartz these catalysts and their influence on the composition of the reactor, a sample of 0.15 g., the fractional composition of reaction products and the mechanism of conversion of specific C 5 which, as the reactor is filled from the bottom of the reactor to hydrocarbons. The study of the mechanism, speed and direction of the lower part of the catalyst boundary, varies from 2.0 to 0.1 individual stages of multistage reactions implemented scientific mm; then the catalyst and quartz were filled, the fractional and industrial processes. Comparison of catalytic properties in the conversion of hydrocarbons of zeolites of different structure and composition of which changed in the reverse order. This other catalytic systems. backfill made it possible to distribute the flow of raw materials evenly throughout the catalyst bed. Then the reactor was placed Keywords—Zeolites, superacid, superacid center, mechanism of in an oven, in which the temperature was raised from room chemical reaction, transformation of pentanes.. temperature to 550 ° C with a heating rate of 20 ° C / min. The sample was kept at T = 550 ° C for three hours in a stream of I. INTRODUCTION air. Then, 15–20 cycles of the reaction (Treac. = 400 ° C) Experimental pulsed microcatalytic apparatus was followed, regeneration (1.5 hours) until a stable activity of the assembled on the basis of a chromatograph, which was - catalyst was achieved. Regeneration was carried out in a stream modified in this way. All gas communications (from the input of dry air (flow rate 1.2 l / h) at T = 550 ° C. Before the of raw materials to the entrance to the column) are thermostated experiment, the regenerated sample was kept at a regeneration at 100 ° C. In order to avoid - the accumulation of high-boiling temperature in a helium current (flow rate 1.2 l / h) for 0.4 hours hydrocarbons on rubber gaskets, the standard dispenser crane is to remove adsorbed water. After all the above operations were replaced on six-running in which such deposits practically were completed, the temperature in the furnace decreased in a current not observed. The dosing crane was also thermostatically helium to Treac., And the sample was kept at this temperature controlled at 100 ° C. A linear temperature rise in the furnace for 0.5 hours to establish and stabilize the required flow rates of was made with the participation of the temperature programmer the carrier gas through the reactor. The flow rate of helium with the speed 20 ° C / min. through the reactor varied, depending on the experimental conditions, in the range of 4-150 ml / min. (0.7.10-7 ÷ 2.5.10-8 m3 / s), according to the calculations carried out in section 2.8. Liquid raw materials were injected into the evaporator with a micrometric syringe in an amount of 8 μl. The temperature in 1 Copyright © 2018, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). 380 Advances in Engineering Research, volume 177 the evaporator was set at 10 ° C above the boiling point of the It should be noted [4, 5] that on the zeolites of the protolytic hydrocarbon under study. Neopentane, gaseous at room cleavage of the C – H bonds of neopentane does not occur, since temperature, was cooled in a refrigerator to -5 ° C and injected iso- and n-pentanes in the primary products of the into the evaporator in the liquid phase with a syringe cooled to transformation are practically absent. the same temperature. At the same time, it is known [6] that, in the presence of The activity and selectivity of the catalysts was determined liquid super-acids of the type HF-SbF5, neopentane along with by the first impulse of the initial hydrocarbon. The activity of cracking undergoes isomerization through penta- (tetra-) the catalysts was monitored by conducting a reference coordinated С-H carbonium-ion with the formation of experiment after each stage of research. isopentane (neopentyl Wagner-Meerwein rearrangement: When studying the effect of Tact, the catalysts after regeneration were treated in a current of helium (flow rate 1.2 l Ме Н Ме Н / h) in the range of temperatures 550-750 ° C for 2 hours. After carrying out these high-temperature treatments, the sample was + + + (Ме)4С + Н + ↔ [Me-C – СН2 ] ↔ (Ме)4С + Н ↔ Me-C – СН2 ↔ not used in other studies. + Ме Н The influence of the degree of coking of zeolites was studied Ме Н by successive introduction of several pulses (10 ÷ 50) of raw + + materials to the catalyst without intermediate regeneration of ↔ Ме3 (С)-СН2 + Н2 ↔ Ме – СН –СН2-Ме the samples. ↔ Ме3 (С)-СН2 + Н2 ↔ Ме – СН –СН2-Ме The superacidic (superacid) catalyst (SCC) passed the Ме Ме preliminary activation at T = 550 ° С for 2 hours in a helium flow (flow rate 1.2 l / h). Since the SCC regeneration is not It is indicated [6] that the preferential protolysis of C – C or followed the experiment, the catalyst activity decreases by a C – H bonds of neopentane is determined by the reaction factor of 10–20 due to a significant release of sulfuric acid from temperature or catalyst composition, in our opinion, by the ratio it) all the experiments performed were performed on a of Bronsted and Lewis acids in the super acid. For example, in superficially activated sample of the sample. the superacid HF-SbF5 (2: 1 ratio), neopentane is predominantly Samples of AOC at temperatures> 60 ° C actively isolated cracked, and in the SbF5 system + traces of HF are hydrohalic acid, which also, like on the SCC, led to an isomerization. irreversible loss of activity, therefore these catalysts underwent Regularities of homogeneous superacid catalysis suggest short-term activation (1/4 hour) at T = 50 ° C in current helium that an increase in the relative concentration of BCC in zeolites before the experiment. and other solid acids should increase the selectivity of the III. TRANSFORMATION OF PENTANES ON AL2O3 protolysis reactions of C – C bonds in hydrocarbons С-Н- ALUMINOSILICATES AND HETEROGENEOUS SUPERACIDS bonds. As applied to pentanes, the protolysis of C – C bonds is considered as the initiating stage of cracking reactions [4, 5], The cracking of pentanes (neo-, iso-, n-pentane) on zeolites and the protolysis of C – H bonds is considered to be from the standpoint of the classical carbenium-ion mechanism isomerization and disproportionation reactions [4–6]. should proceed through the unstable carbocations CH3 + (for all pentanes) and C2H5 + (for iso- and n-pentanes) the formation of The superacid transformation mechanism of iso- and n- which requires high energy getty costs [1]. pentanes on zeolites can be implemented as follows [5]: Obviously, if a classical mechanism is implemented on zeolites for the cracking of pentanes, we should expect a Н + cracking (С1 – С4, number of fundamental regularities, in particular, a higher -С----С С2 + С3) reactivity of iso- and n-pentanes compared to neopentane, Изо-С5Н12 similar compositions of the reaction products and a similar Н Н + isomerization С5 effect on the reaction acidic properties of zeolites. Н-С5Н12 - С - The study of cracking of neopentane in the presence of disproportiation ( С4 + С6) mordenite [2], Y, and CWSC [3] type zeolites suggested that cracking of neopentane proceeds according to the protolytic cleavage mechanism of C – C bonds through penta (tetra–) Based on the foregoing, we systematically investigated the coordinated C – C – carbonium ions with the formation of transformation of neo-, iso- and n-pentanes, and also predominantly methane and butenes in a ratio close to cyclopentane on γ-Al2O3 and AAS CEMCs that were subjected stoichiometric: to the above-mentioned treatments, as a result of which, according to literary data and our physicochemical studies, their acidic properties, including the relative concentrations of BCCs H and LACs in superacid centers of zeolites. In addition, we have investigated dealuminated fujazites (ICF-high-silica fujazites) / \ + + + with increased acidity [7-10] and previously not studied in the (Ме)4С + Н ↔ [Me---C(Me)3] ↔ СН4 + (Ме)3С (4.1) cracking of a number of pentanes. 2 381 Advances in Engineering Research, volume 177 The use of γ - Al2O3 as a catalyst is due to the predominance TABLE II. MOLECULAR WEIGHT DISTRIBUTION OF THE CONVERSION of Lewis acidity in it [1]. PRODUCTS OF N-PENTANE TO AOC, TREAC = 50 ° C, CONVERSION ~ 3 WT.% To compare the catalytic action of zeolites and superacids, The composition of the products the conversion of neopentane on a heterogeneous superacid mol / 100 mol transformed raw materials catalyst of the ZrO2 / SO42- type (SCC) was also studied.
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