The effect of the SiO 2 /Al 2 O 3 molar ratio in Zn/ZSM-5 nanosized zeolites, the nature of original zeolite ZSM-5, and the method of introducing zinc cations into the zeolite structure on its physicochemical and catalytic properties in dimethyl ether conversion to a mixture of synthetic liquid hydrocarbons is studied. It is shown that an increase in the SiO 2 /Al 2 O 3 molar ratio leads to rise in selectivity for liquid hydrocarbons and in the content of isoparaffins and aromatic hydrocarbons in them. The method of zinc incorporation into the composition of nanosized ZSM-5 slightly affects selectivity for liquid hydrocarbons and their group hydrocarbon composition.

The synthesis of hydrocarbons from dimethyl ether in an atmosphere of synthesis gas, over a Pd-Zn-HZSM-5/Al2O3 catalyst, under flow-circulation conditions, at a pressure of 10.0 MPa, was investigated. It was found that the resulting hydrocarbon fractions were characterized by a low concentration of aromatic compounds and high concentrations of iso- and cycloalkanes. The dependence of the yields of the main groups of products and individual components on the contact time was explained in terms of the occurrence of methylation, oligomerization, hydrogenation, H-transfer, and hydroisomerization reactions. The role of Pd and Zn in the formation of the products was evaluated.

Gasoline has been synthesized from oxygenates (dimethyl ether and methanol) on a HZSM-5 zeolite catalyst, modified by palladium and zinc, in a micropilot unit operating in the continuous recycle flow mode. The influence of the gas atmosphere composition—synthesis gas, hydrogen, and methane—on the gasoline selectivity, and on-stream stability of the catalyst has been determined for dimethyl ether (DME) used as a feedstock. The hydrocarbon composition and the carbon distribution in the products have been compared using DME and methanol as the feedstock in the synthesis-gas atmosphere. It has been shown that the higher gasoline selectivity production in the case of methanol is due to the higher concentration of aromatic hydrocarbons, which is achieved by decreasing the intensity of their dealkylation.

The development of single-stage synthesis of dimethyl ether (DME) from synthesis gas makes it possible to obtain hydrocarbons directly from DME. The effect of the nature and concentration of components of the vapor–gas mixture that arrives at the stage of DME conversion to liquid hydrocarbons on activity and selectivity of a zinc–palladium zeolite catalyst has been examined. It has been found that and increase in DME concentration to more than 20 vol % in the reaction stream leads to lowering both DME conversion and gasoline selectivity and increasing the yield of byproducts. The presence of components such as H2, CO, H2O in the vapor–gas mixture ensures high stability of the catalytic system. Switching from the flow-through to the recycle operation mode increases the catalyst selectivity for gasoline, decreases the formation of durene, and reduces catalyst coking.

Технология производства на цеолитах бензиновых фракций (синтетических углеводородов) из синтез-газа (СИ-газа) через стадию получения оксигенатов, разработанная ИНХС РАН, отличается от применяемой в классическом MTG-процессе компании “ExxonMobil” тем, что стадии получения оксигенатов и БФ интегрированы в один контур. В новой технологии в составе синтетических углеводородов в зависимости от отношения Н2 в СИ-газе содержится от 6 до 27 мас. % ароматических углеводородов (бензол и дурол 2 мас. %). При использовании СИ-газа с Н2 3.5 в парогазовой смеси, поступающей на стадию получения бензиновых фракций, наблюдается повышенное содержание метанола (МеОН) и при исчерпывающей конверсии диметилового эфира (ДМЭ) отмечена неполная конверсия МеОН. С целью повышения степени вовлечения МеОН в процесс синтеза бензиновых фракций изучено влияние различных параметров на конверсию МеОН и ДМЭ. Показано, что изменение состава свежего СИ-газа оказывает более заметное влияние на конверсию МеОН, чем на конверсию ДМЭ в синтетические углеводороды и усиливается с увеличением массовой скорости подачи МеОН. Если в составе парогазовой смеси, поступающей из реактора получения оксигенатов на стадию получения бензиновых фракций, присутствует более 50 мас. % МеОН, то для повышения селективности по бензиновым фракциям синтез необходимо проводить при меньших значениях массовой скорости подачи оксигенатов, чем в случае, когда парогазовая смесь содержит только ДМЭ.

The technology for the manufacturing of gasoline fractions (synthetic hydrocarbons) from synthesis gas (syngas) on zeolites through the oxygenate production step as developed at the Topchiev Institute of Petrochemical Synthesis, differs from the classical MTG process of ExxonMobil in that the oxygenate and gasoline production steps are integrated in one circuit. In the new technology, the synthetic hydrocarbons contain 6 to 27 wt % aromatic hydrocarbons (benzene and durene ≤2 wt %) depending on the H2/CO ratio in syngas. When syngas with H2/CO ≤ 3.5 in the vapor-gas mixture arriving at the gasoline production stage is used, an increased methanol (MeOH) content is observed and the MeOH conversion is incomplete with the exhaustive conversion of dimethyl ether (DME). To increase the involvement of MeOH in the synthesis of the gasoline fraction, the influence of various parameters on the conversion of MeOH and DME has been studied. It has been shown that a change in the composition of fresh syngas has a more significant effect notably on the MeOH, rather than the DME conversion into synthetic hydrocarbons and is enhanced with an increase in the MeOH weight hourly space velocity (WHSV). If the vapor-gas mixture arriving from the oxygenate production reactor at the step of production of the gasoline fraction contains more than 50 wt % MeOH, in order to improve the selectivity for the gasoline fraction, the synthesis should be conducted at a lower WHSV of oxygenates than in the case when the vapor-gas mixture contains DME alone.

The effect of the manner and conditions of introducing lanthanum cations into NH4-ZSM-5 zeolite on the properties of catalysts for the conversion of dimethyl ether into the mixtures of gasoline hydrocarbons is studied. The physicochemical properties of synthesized catalysts are studied by means of temperature-programmed ammonia desorption, the adsorption of benzene, atomic absorption spectroscopy, differential scanning calorimetry, and thermogravimetry. It is shown that the degree to which lanthanum cations are replaced by ammonium cations both depends on the conditions of ion exchange in the zeolite and affects its acidity spectrum and the selectivity of the formation of paraffin hydrocarbons with isostructure. It is concluded that an increase in the amount of introduced lanthanum leads to an increase in the content of iso-paraffins from 69 to 76 wt % and a decrease in the content of aromatic hydrocarbons from 10.5 to 5.5 wt % and that of durene from 1.5 to 0.2 wt % in the products.

Изучено влияние способа и условий введения катионов лантана в NH4 ZSM-5 на свойства катализаторов превращения диметилового эфира в смесь углеводородов бензинового ряда. Методами температурно-программированной десорбции аммиака, адсорбции бензола, атомно-абсорбционной спектроскопии, дифференциальной сканирующей калориметрии и термогравиметрии изучены физико-химические свойства синтезированных катализаторов. Показано, что степень замещения катионов аммония катионами лантана зависит от условий проведения ионного обмена в цеолите и влияет на спектр его кислотности и селективность образования парафиновых углеводородов изо-строения. Так сделан вывод, что увеличение количества вводимого лантана приводит к повышению содержания изо-парафинов от 69 до 76 мас. % и уменьшению содержания ароматических углеводородов от 10.5 до 5.5 мас. %, в том числе дурола от 1.5 до 0.2 мас. %, в составе продуктов реакции.