from first principles PP-I-1

PP-III-51The Concept of Interlayer Dynamics and Poly-Functionality of TMS-BasedCatalysts in HDS and Alcohol SynthesisKogan V.M.N.D. Zelinsky Institute of Organic Chemistry, RAS, Moscow, Russiavmk@ioc.ac.ruOn the basis of the fundamental concepts of catalysis by transition metal sulfides (TMS) anew dynamic model of the promoted Mo-sulfide catalysts functioning under HDS conditionshas been developed. The model describes oscillations by sulfur and promoter atoms betweenthe adjacent layers of the slab. The driving force of such processes is the heterolyticdissociation of the gas phase hydrogen and formation of hydride hydrogen linked to apromoter atom. This model correlates with radio isotopic data [1] and an earlier suggested“forcing out” mechanism [1,2] and gives some new interpretations of the importantstatements of the electron theory of promotion and the “rim-edge” model. The present model(Fig. 1) supposes that an AS is non-promoted single cluster located on terminal of the MoS 2slab layer (“rim”) and responsible for hydrogenation. A non-promoted site located on theedges is denoted as “empty site” (ES). Its catalytic properties are the same as of a “slow” site.A “rapid” AS consists of combination of the promoted and non-promoted single clustersplaced on the terminals of the adjacent layers of the MoS 2 slab (Type II) or on the same layer(Type I). The result is that “rapid” sites transform into “slow”/“empty” ones and vice versa.The frequency of such migrations determines the activation degree of the catalyst [3,4].bacFig. 1. (a) The“slow”/“empty”single site; (b) the“rapid” single site; (c)location of the sites ofvarious types on theterminal surface of theCoMoS 2 slab. Colorcode: turquoise – Mo;blue – Co; yellow – S.Basing on the suggested model we can advisedly vary composition and morphology of theactive phase and nature of support aiming to control amount and distribution of the different(AS)s between rims and edges of the slabs in the newly designed catalysts for most effectivehydro-treating of various types of crude [5]. This concept allowed us to assume that thereaction of alcohol formation from synthesis gas proceeds on the same two types of the (AS)s204