Investigation of hydrogen transfer from carbon-14 ring labeled methylcyclohexane during the methanol-to-gasoline reaction

Abstract

The selective conversion of methanol to hydrocarbons using a ZSM-5 catalysts was a significant discovery. The products follow an Anderson-Schulz-Flory distribution but with at least one important exception, the products above C/sub 10/ make an insignificant contribution to total product yield. The mechanism for the polymerization reaction is complex and three of the more widely accepted reaction pathways involve different reaction intermediates: (i) carbocations, e.g., CH/sub 3//sup +/ (ii) carbene (:CH/sub 2/), and (iii) oxonium ion (e.g., (CH/sub 3/)/sub 3/O/sup +/). Common to the above three reaction pathways is the final step(s), dehydrogenation to produce aromatics. There is strong evidence to support the view that the formation of one aromatic molecule is accompanied by the formation of three alkane molecules. To obtain information about the contribution of this reaction to the methanol-to-gasoline synthesis, a mixture of methanol and /sup 14/C-labeled methylcyclohexane has been converted using an HZSM-5 catalyst. Determining the distribution of /sup 14/C in the products would permit at least a semiquantitative measure of the importance of cyclohexane dehydrogenation as well as cycloalkane isomerization and cracking in the overall reaction work. 7 references.