Zeolite-containing Catalysts Research Articles

Prediction of residue coke content and operating modes of regenerator in the catalytic cracking technology

This work is aimed at predicting the amount of residue coke and the temperature of operating mode of the regenerator, depending on the initial technological conditions of the process during regeneration of catalyst coked at various degrees (0.4–0.6% wt.). Numerical studies were performed using a mathematical model that takes into account the physicochemical regularities of the regeneration process for zeolite-containing catalysts and making it possible to predict not only the amount of the residual coke and the flue gas composition of regeneration, but also the temperature in the regeneration zone. It has been stated that when changing the amount of coke on the coked catalyst from 0.4 to 0.6% wt., the regeneration temperature must be maintained in the range of 673.8–712.8 C to achieve the degree of coke conversion at the level of 92% and to prevent the irreversible deactivation of the catalyst.

Transformation of Paraffin and Olefin Hydrocarbons on a Modified Zeolite-Containing Catalyst of Cracking

Industrial zeolite-containing OMNIKAT-210P catalyst modified with Ni, Co, Cr is used as a catalyst to study the conversion of hydrocarbons contained in catalytic cracking gases. The aim of the study is to obtain a high-octane component of gasoline. The metals are deposited on nanosized particles of a zeolite-containing catalyst. The particle size is at a level of (5–10) × 10−9 m. The particle size allows metals Ni, Cr, Co to be applied evenly on the surfaces of the nanoparticles. The particles then form balls 2–3 mm in size that are dried (120°C) and calcined (450–500°C). The yield of liquid products is at a level of 48.3–30.3 wt %, depending on the time of sampling.

Integrated mathematical modeling of catalytic cracking and zeolite-containing catalyst oxidative regeneration

The work is aimed at establishing the thermodynamic, kinetic and hydrodynamic regularities of the vacuum gas oil catalytic cracking and the zeolite-containing catalysts regeneration, which served as a catalytic cracking reactor mathematical model development basis. The prediction calculations ensured the catalyst circulation ratio optimization depending on the catalyst flow temperature after regeneration. To maintain the gasoline fraction maximum yield (58.47 and 58.38 wt%) it is necessary to keep the catalyst circulation ratio at the level of 6 and 9.5 tonscat/tonsfeed if the catalyst flow temperature after regeneration are 700 and 650 °C, respectively.

Conversion of the Propane-Butane Fraction into Arenes on MFI Zeolites Modified by Zinc Oxide and Activated by Low-Temperature Plasma.

The effect of modification of MFI zeolite 1–5 wt.% ZnO activated by plasma on acid and catalytic properties in the conversion of the propane–butane fraction into arenes was investigated. The high-silica zeolites with silicate module 45 were synthesized from alkaline alumina–silica gels in the presence of an ‘X-oil’ organic structure-forming additive. The modification of the zeolite with zinc was carried out by impregnating the zeolite granules in the H-form with an aqueous solution of Zn(NO3)2. The obtained zeolites were characterized by X-ray phase analysis and IR spectroscopy. It is shown that the synthesized zeolites belong to the high-silica MFI zeolites. The study of microporous zeolite-containing catalysts during the conversion of C3-C4 alkanes to aromatic hydrocarbons made it possible to establish that the highest yield of aromatic hydrocarbons is observed on zeolite catalysts modified with 1 and 3% ZnO and amount to 63.7 and 64.4% at 600 °C, respectively, which is 7.7–8.4% more than on the original zeolite. The preliminary activation of microporous zeolites modified with 1–5% ZnO and plasma leads to an increase in the yield of aromatic hydrocarbons from the propane–butane fraction; the maximum yield of arenes is observed in zeolite catalysts modified with 1 and 3% ZnO and activated by plasma, amounting to 64.9 and 65.5% at 600 °C, respectively, which is 8.9–9.5% more than on the initial zeolite. The activity of the zeolite catalysts modified by ZnO and activated by plasma show good agreement with their acid properties. Activation of the zeolites modified by 1 and 3% ZnO and plasma leads to an increase in the concentration of the weak acid sites of the catalyst to 707 and 764 mmol/g in comparison with plasma-inactivated 1 and 3% ZnO/ZKE-XM catalysts at 626 and 572 mmol/g, respectively.

ГИДРОПЕРЕРАБОТКА ДИЗЕЛЬНЫХ ФРАКЦИЙ НА МОДИФИЦИРОВАННОМ АЛЮМОНИКЕЛЬМОЛИБДЕНОВОМ КАТАЛИЗАТОРЕ КГО – 12

The paper presents the results of the study of hydrotreatment of hexane, decane and diesel oil fractions on a new aluminum oxide zeolite-containing catalyst KGO – 12, modified with metals with variable valence, phosphorus and lanthanum additives. The hydrotreatment process was studied in a high-pressure flow unit with a stationary catalyst bed at temperatures of 320 – 400° C, a pressure of 4.0 MPa, and a volumetric feed rate of 2 h-1. After hydrotreating the diesel fraction of oil on the KGO – 12 catalyst at 400° C, the sulfur content in the catalysate decreases from 0.141 to 0.0092%, and the solidification temperature decreases from minus 27 to minus 57° C. The study of the process of hydrotreatment of the n-alcanes diesel fraction on the KGO – 12 catalyst showed that hydrotreatment, hydroisomerization and hydrocracking reactions occur simultaneously. It is established that the developed KGO – 12 catalyst has a high activity in the process of hydrotreating the diesel fraction of oil and makes it possible to obtain low-setting low-sulfur diesel fuel.

CONVERSION OF PROPANE-PROPYLENE FRACTION INTO AROMATIC HYDROCARBONS ON MODIFIED ZEOLITE CATALYSTS

The process of transformation of propane-propylene fraction into aromatic hydrocarbons on zeolitecontaining catalysts modified Zn, La, Cr, Zr and P was discovered. The process was carried out in an installation in aflow installation at atmospheric pressure with a temperature variation from 350 to 600°C and a volumetric feed rateof 150-1020 h-1. The catalysts were prepared by impregnation of aluminum hydroxide and zeolite ZSM-5 withaqueous solutions of nitric acid salts of metals and phosphoric acid. The physical and chemical characteristics of thedeveloped catalysts are studied. The BET method established that the surface of the developed catalysts fluctuateswithin 211.0-274.0 m2/ g of the catalyst. Catalysts are predominantly mesoporous: pores with d ≈ 2.0-3.0 nmpredominate.It is shown that the developed modified zeolite-containing catalysts have high catalytic activity and selectivityin the process of processing the propane-propylene fraction into aromatic hydrocarbons. The predominant productsformed during the processing of C2-C4 alkanes are toluene and benzene. It was found that the highest yield ofaromatic hydrocarbons is 52.8% (550°С, 150 h-1) on the catalyst Zn-La-Р-Cr-ZSM-Al2O3 with a conversion rate of100.0%, selectivity for aromatic compounds - 52.8%.Modified zeolite-containing catalysts have multifunctional properties. The composition of liquefied petroleumgas processing products shows that the formation of aromatic hydrocarbons occurs in one stage as a result ofcracking, dehydrogenation, oligomerization, dehydrocyclization, alkylation reactions

Transformation of paraffin and olefin hydrocarbons on the modified on the zeolite-containing cracking catalyst

As a catalyst for studying the conversion of hydrocarbons contained in catalytic cracking gases, a modified Ni, Co, Cr industrial OMNIKAT-210P zeolite-containing catalyst was used. The purpose of the research is to obtain a high-octane component of gasoline. The deposition of metals was carried out on nano-sized particles of a zeolite-containing catalyst. Particle size was at the level of (5÷10)·10–9m. The particle size allows you to evenly apply the metals Ni, Cr, Co on the surface of the nanoparticles. Then the particles are molded in the form of balls with a size of 2–3 mm and subjected to drying (120 °С) and calcining 450–500 °С. The yield of liquid products is at the level of 48.3–30.3 % of the mass.

Molecular-Sieve Catalysis: Pioneering Works of the Chemists of Moscow State University

A short review was given of the most important results of the theoretical and experimental studies at the Kinetics and Catalysis Laboratory, Department of Chemistry, Moscow State University, at the initial stage of the development of molecular sieve catalysis, when the procedure for the synthesis of crystalline aluminosilicates (zeolites) was developed and industrial-scale production of zeolites and zeolite-containing catalysts was launched. These results underlie further development of molecular sieve catalysis as a scientific basis for the production of Russian-made zeolites and catalysts for large-scale oil refining and petrochemical processes.

Conversion of Oxygenates to Aromatic Hydrocarbons on a Commercial Zeolite Catalyst: Comparison of Ethanol and Dimethyl Ether

Conversion of oxygenates to aromatic hydrocarbons in the syngas medium in the presence of a commercial zeolite-containing catalyst was studied. The influence of pressure on aromatization of dimethyl ether and ethanol was examined. At 400°C, an increase in the pressure from 0.1 to 3.0–10.0 MPa leads to a sharp increase in the yield of aromatic compounds. Dimethyl ether and ethanol, which are isomers belonging to different classes of compounds, were compared as substrates in conversion to aromatic hydrocarbons. At elevated pressure, dimethyl ether compared to ethanol exhibits higher selectivity in formation of the desired synthesis products, allowing synthesis of liquid hydrocarbons with increased content of arenes.

Effect of the Texture and Acidity of a Zeolite-Containing Support on the Activity and Selectivity of NiMoS Catalysts in Hydrogenation and Hydrocracking Reactions

Supports based on pseudoboehmite, ultrastable zeolite Y, and ZSM-5 with different silica ratio and concentration of acid sites are prepared. NiMoS catalysts are synthesized by the incipient wetness impregnation of the prepared supports by the joint solution of H3PMo12O40 and nickel citrate. The composition and properties of the supports and catalysts are studied by low-temperature nitrogen adsorption, ammonia temperature-programmed desorption, IR spectroscopy of pyridine adsorption, and high-resolution transmission electron microscopy. Catalytic properties are investigated in dibenzothiophene hydrodesulfurization (HDS), naphthalene hydrogenation (HYD), and hexadecane hydrocracking (HC) concurrent reactions in a flow unit equipped with a microreactor. It is shown that the HDS activity of the synthesized samples declines as the dispersity of active-phase particles decreases in correlation with a change in the surface area of support mesopores. It is shown that the NiMo/ZSM-5/23 catalyst exhibits a high activity in naphthalene HYD and subsequent reactions of tetralin and decalin naphthene ring opening and hexadecane HC. It is found that the activity of zeolite-containing catalysts in naphthalene HYD grows with the proportion of Bronsted acid sites.

Bimetallic Sulfur Reduction Additives Based on Alumosilicate of Al-MCM-41 Type For Cracking Catalysts: Desulfurazing Activity vs. Ratio of Components in a Support

Sulfur reduction additives have been synthesized based on an ordered mesoporous aluminosilicate of Al-MCM-41 type and alumina with a different ratio of components in a support for cracking catalysts. Supports and additives for cracking catalysts were characterized by transmission electron microscopy, FTIR spectroscopy, low-temperature nitrogen adsorption/desorption, and thermoprogrammed ammonia desorption. Catalytic tests of additives with an industrial zeolite-containing cracking catalyst were carried out, and their sulfur reduction activity was demonstrated. It was found that with an increase in the proportion of mesoporous aluminosilicate in the composition of the additive, the sulfur reduction activity rises. The use of additives reduces the amount of sulfur in the liquid cracking products of vacuum gas oil up to 27 rel % compared with the use of a catalyst without the additive.

Conversion of Associated Petroleum Gas into Aromatic Hydrocarbons

The possibility of the efficient catalytic synthesis of hydrocarbons on a zeolite-containing catalyst modified with zinc oxide for several reaction–regeneration cycles is studied. An estimate of the interregeneration run time shows that it could be at least 130–150 h, which is quite long for such a high-temperature process. The dependences of the conversion of gases rich in C3–C4 within the composition of the associated petroleum gas on the temperature and time of the reaction are established.

Controlling the Ratio of the Reactions of Intermolecular Hydrogen Transfer and Cracking on Setups with Fixed and Recycled Catalyst Beds

The effect of the main parameters (temperature, pressure, and dilution of the reaction medium with an inert gas) of such catalytic processes as the cracking of vacuum gasoil and the hydrogenless refining and cracking of gasoline fractions on the ratio of the selectivity of the cracking and intermolecular hydrogen-transfer reactions is studied. Control over the ratio of these reactions allows products to be obtained according to the requirements for processing feedstocks. An increase in the time of feedstock–catalyst contact, a reduction in the degree of diluting the reaction mixture with an inert gas, and a rise in pressure result in greater selectivity for hydrogen-transfer reactions. Experiments are performed on setups with fixed and recycled beds of zeolite-containing catalysts. The transformation of feedstocks containing deuterated compounds is investigated.

Catalysts for Synthesizing Liquid Hydrocarbons from Methanol and Dimethyl Ether: A Review

Different ways of increasing the selectivity of catalysts are described for converting oxygenate to liquid hydrocarbons. Analysis of reports suggests that the main factors affecting the selectivity of zeolite-containing catalysts are the structural type and acidic properties of the zeolites. It is shown that the strength and distribution of acid sites depend on the structural type and chemical composition of the zeolite framework, and on the chemical nature of the exchange cations. Different ways of changing the acidic properties of zeolites are discussed, e.g., modifying them with cations of various elements and subjecting them to postsynthesis acidic, alkaline, and steam heat treatment.

HLaY-and HCeY-Containing Heavy Vacuum Gas-Oil Cracking Catalysts Based on Fe-Pillared Montmorillonite

Cracking of heavy vacuum gas oil on HCeY and HLaY zeolite-containing catalysts deposited on Fe-pillared montmorillonite is characterized before and after steam treatment. Special attention is paid to thermally stable HCeY-containing catalyst that gives greater yields of gasoline and gas phases than HLaY-containing catalyst. Correlations of activity with the number and strength of acidic sites are found.

Catalysts for Synthesis of Liquid Hydrocarbons from Methanol and Dimethyl Ether: Review

Various methods for improving the catalyst selectivity to conversion of oxygenates to liquid hydrocarbons are discussed. Literature analysis reveals that the key factors determining the selectivity of zeolite-containing catalysts are the structure type and acid properties of the zeolite. The strength and distribution of the acid sites are shown to depend on the structure type and chemical composition of the zeolite framework, as well as on the chemical nature of exchange cations. Methods for changing acid properties of zeolites are considered, among which are modifying with various cations, post-synthetic acid, alkali or steam treatment.

Development of Kinetic Model of Alkylation Of Isobutane By Olefins at Zeolite-Containing Catalysts

A kinetic model that covers the key reactions for alkylation catalyzed by zeolites is presented. It represents a system of ordinary first-order differential equations and forms the basis of successive construction of a computer modelling system. During investigation of the alkylation of isobutane by olefins a scheme was compiled for the conversion of hydrocarbons, and differential equations describing the rates of the chemical reactions involved in the alkylation of isobutane by olefins were formulated. The kinematic parameters of the reactions were determined by seeking the reaction rate constants in a solution of the reverse kinematic problem. The initial data for solving the inverse kinetic problem are also the technological mode of operation of the pilot plant and the composition of the products of the alkylation process. A set of differential equations was formulated in order to solve the computer model under the initial conditions of the alkylation process for the overall chemical reactions of each group of substances without taking account of some of the intermediate reactions. The system of differential equations was solved by the Euler method with the subsequent production of a better set of reaction rate constants for each record in the experimental data.

Application of Oxidative Regeneration of Zeolite-Containing Catalysts to Solid-Acid Alyklation of Isobutane by Olefins

Application of oxidative regeneration of zeolite-containing catalysts to alkylation of isobutane by olefins was investigated during long-term catalyst tests at a pilot plant. This approach to regeneration was found to shorten the catalyst service life between regenerations. Local overheating of the catalyst is presumed to cause irreversible sintering and, as a result, a decrease of alkylate yield

In Russian

For the first time, it is demonstrated that the methanol diffusion in the H-ZSM-5/Al 2 O 3 catalyst pellet is anomalous and is described by the time-fractional diffusion equation. The regime of the methanol transport is sub-diffusive. The aim of the present work is a description of the experimental data of the methanol transport through the pellet of the zeolite-containing catalyst for olefins synthesis form the methanol based on the solutions of the diffusion equation of the second Fick’s law of diffusion and the time-fractional diffusion equation. In this work, the mesoporous catalyst based on zeolite H-ZSM-5 and alumina with zeolite/alumina ratio 3/1 by mass is used. The methanol transport has been studied using the developed method of mass transfer process investigation in the porous solid media in flow regime. The method is based on the porous sample saturation by a pulse of the adsorbate. The porous sample is installed to the diffusion cell. Adsorbate quantity evolution versus time is chromatographically analyzed. The porous sample is installed to the diffusion cell so that half of its surface is impermeable for adsorbate which allows applying the von Neumann boundary conditions to sole the diffusion equation. The investigation resulted in the obtaining the relative concentration decay versus time on the boundary of the catalyst pellet. The obtained experimental dependences are analyzed on the whole temporal scale using the analytic solution of the diffusion equation based on the second Fick’s law of diffusion. However, the correspondence between the theoretical solution and the experimental data is very poor. The asymptotic analysis of the experimental data in the long-time range linearized in the logarithmic coordinates according to the solution of the standard diffusion equation has demonstrated that the equation for the second Fick’s law of diffusion is inapplicable to a description of the obtained experimental data because the slope of the experimental data is far from the theoretical one which is equal to unity. On the other, an hand analysis of the experimental data in the long-time range linearized in the logarithmic coordinates according to the solution of the time-fractional diffusion equation revealed the high correlation between the theoretical solution and the experimental data. The calculated values of the fractional order and the fractional diffusion coefficient are independent on the experimental conditions. This means that these characteristics are individual for each pair of the porous media and diffusate and may be associated with the methanol adsorption on the active sites on the surface of the catalyst. The fractional order value is lower than unity, which reveals the presence of the sub-diffusive regime of transport, which is slower comparing to the standard diffusion. Based on the analysis of the methanol mass transfer in the pellet of the zeolite-containing catalyst, it is found that the solution of the time-fractional diffusion equation gives good fit to the experimental data comparing to the solution of the standard diffusion equation. The values of the diffusion coefficients and the fractional orders calculated on the long times are equal to the values estimated for the whole temporal range. It is found that the methanol transfer in the catalyst pellet occurs in the slow sub-diffusive regime. The experimental evidence of the presence of an anomalous diffusion is fundamental for the theoretical understanding the mass transfer process and modeling as well as for application during solving the engineering problems.

Alkylation of Isobutane by Olefins on Zeolite-Containing Catalysts with in-situ Catalyst Regeneration

One solution of the problem of deactivating zeolite-containing alkylation catalysts is to use supercritical conditions in the process where the supercritical hydrocarbon fluid that is formed removes the high-molecular-weight condensation products formed on the catalyst surface. This paper reports the results of prolonged pilot tests of catalysts based on modified polycation-decationized Y zeolites in an ultrastable form in alkylation with in-situ catalyst regeneration.