Abstract: Hydroisomerization of n-paraffins over bifiinctional catalysts, i.e., acidic support containing small amounts of a hydrogenating/dehydrogenating component such as Pt or Pd, is used to increase the low temperature performance of diesel fuels and to obtain high viscosity index lube oils [1], These isomerization reactions involve the hydrogenation/dehydrogenation steps on metallic sites and the formation of carbenium ions with their subsequent skeletal rearrangement into mono-, di- and multibranched species on acid sites of the catalyst. Actually the hydroconversion of long-chain n-paraffins along with the isomerization reaction is accompanied by cracking of the carbon-carbon bond by β-scission. As expected from classical carbenium ion chemistry, multibranched paraffin isomers are cracked more easily. Thus, the balance between both strength and concentration of acid sites and shape-selective constraints imposed on attainable geometry of alkylcarbenium ion by acidic support should strongly influence the isomerization selectivity of the bifunctional catalyst. The presence of mild acidity and the shape selective zeolitic features has spurred a widespread interest to new catalytic materials such as silicoaluminophosphate (SAPO) base catalysts for the hydroisomerization of paraffînic feedstocks. Precondition of low, if any, formation of di- and multibranched isomers restricts the pore size and channel architecture of possible SAPO materials to structures with one-dimensional channel system and pore mean diameter not exceeding 5.8 Å 2. and 3.. The most appropriate candidates are microporous silicoaluminophosphates with AEL, ATO and AFO type structures. At present the industrial process of lube oil dewaxing (ChevronTexaco) is realized on bifimctional catalyst with acidic SAPO-11 (AEL) component. Few examples in the literature devoted to comparative study of AEL-, ATO- and AFO-SAPO materials in hydroisomerization reaction are based on a single specimen of each catalyst, sometimes not phase-pure and often prepared by exotic or undefined method. Recently the authors found a new method for selective and reproducible synthesis of SAPO-31 (ATO type structure) materials in the presence of di-n-pentylamine and showed hydroisomerization efficiency of catalysts based on these systems 3. and 4., In the present work an influence of parameters of preparation of SAPO-31 - based bifimctional catalysts is demonstrated in terms of their catalytic performance in hydroconversion of n-octane.

Cite: Kikhtyanin O.V. , Toktarev A.V. , Echevsky G.V.
Preparation Factors Influencing the Effectiveness of SAPO Catalysts in n-Paraffins Hydroisomerization
In compilation Scientific Bases for the Preparation of Heterogeneous Catalysts. 2006. – C.897-904. DOI: 10.1016/S0167-2991(06)80995-X Scopus РИНЦ ANCAN OpenAlex

Dates:

Published print:	Jan 1, 2006
Published online:	Sep 2, 2007

Identifiers:

Scopus:	2-s2.0-35048832929
Elibrary:	13516486
Chemical Abstracts:	2008:289074
Chemical Abstracts (print):	149:227374
OpenAlex:	W56999539

Citing:

DB	Citing
Scopus	6
Elibrary	6
OpenAlex	4

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