Production, Physicochemical and Catalytic Properties of Gallium-Containing Zeolite Catalysts

Crystalline galloalumino- and gallosilicates with pentasil structure were synthesised under hydrother-mal conditions. The influence of gallium concentration and binder amount both on physicochemical and catalytic properties of a zeolite in the process of C2-C4 light alkanes aromatization and on catalyst deacti-vation due to carbidization has been studied. Acidic properties of gallium-containing pentasils with differ-ent composition were studied using the method of thermoprogrammed ammonia desorption. The forma-tion of strong aproton acidic sites whose composition includes gallium ions was found. It has been shown that isomorphic aluminium replacement by gallium in the pentasil lattice leads to a significant increase in aromatizing activity and period of stable catalyst operation. A decrease in intensity of coking and the formation of less condensed coke deposits with a wide distribution by the structure are observed with the increase in gallium concentration. The introduction of a binder to galloaluminosilicate results in a signifi-cant increase in mechanical strength of a catalyst. It was established that the most efficient catalyst of the above process is a zeolite containing 2.2% of gallium oxide and 1.3% of aluminium oxide and mixed with 20% of the pseudobeumite. The selectivity of the formation of aromatic hydrocarbons reaches 55-60%, the period of stable operation exceeds 350 h. In accordance with the data obtained suggested are the principles of the selection of efficient catalysts of light alkanes aromatization and optimum conditions of the process

Investigation of the Process and Products of the MASHS Interaction of Silicon Dioxide with Magnesium Reparation in the Carbon-Free Method for Obtaining Silicon

Mechanocomposites SiO2 / Mg with different component ratios were obtained. It was demonstrated that chemical interaction between the components in these systems starts at lower temperatures. The products of the SHS process with SiO2 / Mg mechanocomposites as precursors are mainly silicon and magnesium oxide; in addition, magnesium silicate and silicide are formed. After the treatment of the product in three stages with different acids, silicon was obtained in the form of agglomerates about 500-1000 nm in size, compoused of smaller particles about 50-80 nm. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3493

Thermocatalytic conversion of petroleum paraffin in the presence of tungsten carbide powders

Russia occupies the third place in the world in terms of stocks of heavy oil raw materials. The development of deposits of light and medium oils makes it inevitable to involve heavy, as well as residual, petroleum raw materials in processing to meet the growing demand for petroleum products. Increase of the depth of oil processing possible in various ways, one of which is the use of new efficient catalysts, resistant to corrosion, poisoning and coking. Tungsten carbide, meeting these requirements, is a promising starting compound for the production of cracking catalysts for heavy oil feedstocks. The influence of tungsten carbide and its calcination temperature on the composition and yield of oil paraffin cracking products on the resulting catalysts was studied to investigate its catalytic activity, the optimum treatment temperature of tungsten carbide was determined. The high catalytic activity of a WC sample calcined at 420°C is shown. Using the physicochemical methods of investigation, the properties of tungsten carbide samples, as well as the composition and properties of the paraffin cracking products in the presence of the catalysts obtained, were studied

Investigation of Massive Catalyst based on Molybdenum Disulphide by Simultaneous Thermal Analysis and Mass Spectrometry Methods

The paper presents the results of experimental studies of massive sulfide catalysts by simultaneous thermal analysis and mass spectrometry. It is found that the STA/MS methods are quite informative for testing the catalyst systems based on MoS2 and are useful in identification of the reference features that could be used to predict their activity. It is also shown that the defect structure of molybdenum disulfide formed during mechanical activation is reflected on the DSC curves

Generation of Liquid Products from Natural Gas over Zeolite Catalysts

The main component of the natural gas is methane, whose molecules are characterized by a high chemical and thermal stability. It is impossible to perform the chemical transformation of natural gas into liquid organic compounds without applying highly active polyfunctional catalysts. Natural gas might be converted into liquid products in the presence of zeolite catalysts of pentasil family. Zeolite catalysts of ZSM-5 type were prepared to realize the process. They contained various amounts of Zn and Ga promoters introduced by ion exchange and impregnation. It has been shown that in the presence of small amounts of C2-C5 alkanes in the feedstock the methane is converted into aromatic hydrocarbons much more readily and in softer conditions than pure methane. At optimum process conditions reached is a high conversion of the natural gas into a mixture of aromatic hydrocarbons. This mixture mainly consists of benzene and naphthalene and small amounts of their derivatives – toluene, C8 and C9+ alkylbenzenes, methyl- and dimethylnaphthalenes. An optimum composition of zeolite matrix and the amount of the modifier in the catalyst have been established

A Model of Catalytic Cracking: Product Distribution and Catalyst Deactivation Depending on Saturates, Aromatics and Resins Content in Feed

The problems of catalyst deactivation and optimization of the mixed feedstock become more relevant when the residues are involved as a catalytic cracking feedstock. Through numerical and experimental studies of catalytic cracking, we optimized the composition of the mixed feedstock in order to minimize the catalyst deactivation by coke. A pure vacuum gasoil increases the yields of the wet gas and the gasoline (56.1 and 24.9 wt%). An increase in the ratio of residues up to 50% reduces the gasoline yield due to the catalyst deactivation by 19.9%. However, this provides a rise in the RON of gasoline and the light gasoil yield by 1.9 units and 1.7 wt% Moreover, the ratio of residue may be less than 50%, since the conversion is limited by the regenerator coke burning ability

Acidic and Catalytic Properties of Mo-Containing Zeolite Catalysts for Non-Oxidative Methane Conversion

The conversion of methane into benzene, toluene and naphthalene at the reaction temperature of 750 В°C and gas hourly space velocity (GHSV) of 500-1500 h-1 over zeolites modified via impregnation with ammonium heptamolybdate and mechanical mixing with Mo oxide and nanopowder is studied under non-oxidative conditions. It has been established that the highest methane conversion per one run and maximal yield of aromatic hydrocarbons are reached for the sample containing 4.0 mass.% the Mo nanopowder. The stability of Mo-containing zeolite catalysts in the process of methane dehydroaromatization at different GHSV has been studied and a characteristic presence of the induction period caused by the formation of active Mo forms both on the external surface and into the zeolite channels has been established. Both the duration of induction period and stable catalyst operation are decreasing with increasing of GHSV. It was demonstrated that acidic properties of a Mo-containing zeolite catalyst depend on the Mo concentration and method of its introduction

Влияние щелочной обработки на физико-химические и каталитические свойства цеолита типа ZSM‑5 в процессе превращения прямогонной бензиновой фракции нефти

Postsynthetic treatment of a ZSM‑5 type zeolite with aqueous solutions of NaOH of various concentrations is carried out. Structural, acidic, and catalytic properties of the initial zeolite and treated samples are investigated in the course of conversion of straight-run gasoline fraction of oil. The main operational characteristics of the obtained high-octane gasolines are determined. The dynamics of deactivation of the initial ZSM‑5 zeolite and the sample subjected to alkaline treatment is reported and the structure of coke deposits is studied. It is found out that alkaline treatment of zeolites leads to a decrease in their crystallinity, specific surface area and specific mesopore volume, while the average pore diameter increases. Also a decrease in the concentration of acid sites with an increase in their strength is observed. As a result of changes in the properties of zeolites, the performance and stability of the catalysts obtained on their basis increase, which contributes to the improvement of the quality of gasoline formed over these catalysts during the conversion of straight-run gasoline fraction of oilПроведена постсинтетическая обработка цеолита типа ZSM‑5 водными растворами NaOH различной концентрации. Исследованы структурные, кислотные и каталитические свойства исходного цеолита и обработанных образцов в процессе превращения прямогонной бензиновой фракции нефти. Определены основные эксплуатационные характеристики полученных высокооктановых бензинов. Приведена динамика дезактивации исходного цеолита ZSM‑5 и образца, подвергнутого щелочной обработке, изучена структура коксовых отложений. Установлено, что щелочная обработка цеолитов приводит к снижению их кристалличности, величины удельной поверхности и удельного объёма мезопор, увеличению среднего диаметра пор, уменьшению концентрации кислотных центров и увеличению их силы. В результате происходящих изменений свойств цеолитов повышается производительность и стабильность работы катализаторов, полученных на их основе, а также улучшается качество бензинов, образующихся на них в процессе превращения прямогонной бензиновой фракции нефт