| Popis: |
The effect of zeolite silylation using tetraethyl and tetramethyl orthosilicate on the enhancement of para-selectivity and of yields of p-ethyltoluene in toluene alkylation with ethylene was investigated for different Si loadings. It was found that zeolite silylation caused a substantial increase in the selectivity and yield of p-ethyltoluene. Data on changes in sorption capacity, in the number of surface and inner strong acid OH groups, in the rate of uptake of p-ethyltoluene together with the catalytic activity of zeolite and its deactivation indicate that the silylation is restricted to surface and subsurface zeolite layers. The enhancement of para-selectivity and yield of p-ethyltoluene are controlled predominantly by changes in geometry of pore openings and thus by transport rates of ethyltoluenes. |
