CONVERSION OF C₄-FRACTION OF LIQUEFIED PETROLEUM GAS ON ZEOLITECONTAINING CATALYST MODIFIED WITH CHROMIUM AND PHOSPHORUS

Abstract

A zeolite-containing catalyst modified with chromium and phosphorus additives has been developed. The technological conditions of its optimal activity in the dehydrogenation reaction and oligomerization of the C4 fraction of liquefied petroleum gas to produce gasoline components are determined.A study of the physicochemical properties of a 5% Cr/Al2O3+ HZSM catalyst promoted with 5% phosphoric acid was carried out. The structure of the catalyst was studied by electron microscopy in combination with microdiffraction. The reflections of HZSM and Al2O3 were detected using the X-ray diffraction method. It was also shown by the EPR method that the PFK-9 catalyst is characterized by a narrow singlet symmetrical EPR signal with a g-factor of 1.96 and a width ∆Н=60 Gauss against the background of a broad signal with ∆Н=1000 Gauss. The narrow EPR signal is due to Cr5+ ions in the matrix and HZSM zeolite. The intensity of the Cr5+ signal in the PFK-9 catalyst is 205 conventional units. The specific surface area of the catalyst is 176,5 m2/g, the pore volume is 0,137 ml/g.The catalyst at contact with C4-alkanes (400-600°C, P=0,1 MPa) makes dehydrogenation with reception olefins with the subsequent them oligomerisetion. A study of the conversion of the C4 fraction of LPG on the PFK-9 catalyst was also carried out in the presence of water vapor.The yield of C5-C10-hydrocarbons depending on technological conditions fluctuates within 40-50%, at the degree of conversion raw material 80-90%.