Isopropanol to Hydrocarbons Transformation Particularities on Hybrid Zeolite H-ZSM-5 and H-Beta Systems

Abstract

The continuous depletion of hydrocarbon sources contributes to a wide study of the use of biorenewable raw materials to obtain synthetic hydrocarbons from them. Isopropyl alcohol is traditionally produced by chemical hydration of propylene, however, with the development of biotechnology, broad prospects have opened for its production by fermentation of glucose-containing substrates obtained from agricultural and forestry waste. This way, isopropyl alcohol can also be considered as a bio-renewable raw material and it can be widely used for the production of chemical synthesis products, including hydrocarbons. One of the possible ways of processing isopropyl alcohol is the catalytic transformation of alcohols on zeolites and zeotypes of various natures with the formation of hydrocarbons. Currently, zeolite H-ZSM-5 and zeotype SAPO-34 are the most frequently used catalysts for the transformation of alcohols into hydrocarbons, however, their rapid deactivation due to the formation of a carbon residue remains an unresolved problem. The formation of core-shell structures with H-ZSM-5 zeolite in center and an outer shell consist of H-Beta zeolite with large pores can reduce the deactivation of zeolite because of increase in reagents diffusion rate. In this article is devoted to synthesis of ZSM-5/Beta sample with a core-shell structure, as well as a study of its catalytic and physicochemical properties. To form the H-ZSM-5 zeolite, a colloidal solution of tetrapropylammonium hydroxide, a colloidal solution of silicon oxide, aluminum oxide, sodium hydroxide of distilled water was used. The colloidal solution was placed in an autoclave, heated to 140 °C and kept at this temperature for 48 hours, after which the crystals formed were centrifuged, washed with distilled water and kept in a 1M solution of ammonium nitrate for a day. Then, to form the H-Beta layer, H-ZSM-5 was suspended in a colloidal solution consisting of tetraethylammonium hydroxide, tetraethylammonium chloride, a colloidal solution of silicon oxide, sodium hydroxide, sodium chloride and distilled water. The suspension was placed in an autoclave and kept at a temperature of 140 °C for 48 hours, followed by centrifugation, washing in distilled water, suspended in a 1M solution of ammonium nitrate, with repeated washing with distilled water, drying and calcining at 600 °C. Testing of the synthesized of H-ZSM-5/Beta zeolite sample showed a significant decrease in the rate of deactivation compared to the synthesized sample of H-ZSM-5; it is also necessary to note a slight increase in the fraction of liquid hydrocarbons for the sample H-ZSM-5/Beta.