PECULIARITIES OF THE FORMATION OF CONDENSATION PRODUCTS ON THE CATALYST SURFACE UNDER HYDROTREATING CONDITIONS

Al-Co-Mo catalysts coked by individual benzene and thiophene are studi ed using a combined derivatograph-spectrophotometer-chromatograph setu p in an inert gas flow. Benzene condensation products (CP) are condens ed to a greater extent, as follows from the comparison of the composit ion of destruction products, their ratio, and E, values of the overall decomposition process. The existence of a ''surface,'' a more saturat ed layer of CP, whose properties do not depend sufficiently on the nat ure of the initial feedstock, is assumed. A correlation between the qu antity of the sulfur removed and the quantity of CP formed is observed while hydrotreating a real feedstock in the presence of catalysts dif fering in composition and preparation. It was concluded that the compl eteness of hydrodesulfurization is an important factor affecting the C P quantity. The contributions of the products formed during the C-S bo nd cleavage to coke formation and CP composition, particularly, to the ratio of soluble to unsoluble parts, are apparently due to the relati onship between the catalyst hydrodesulfurization capability and its hy drogenation activity with respect to aromatic hydrocarbons and olefin structures.