Alkylation of naphthalene with methanol over SAPO-11 molecular sieve synthesized by different crystallization methods

Abstract

Silicoaluminophosphate SAPO-11 molecular sieves were synthesized by both traditional hydrothermal and microwave irradiation methods. Their properties were characterized by multiple physico-chemical methods and compared in the alkylation of naphthalene with methanol. The results obtained indicate that the different preparation methods result in differences in the characteristics of the prepared samples. Compared to SAPO-11 obtained by the traditional hydrothermal method, samples synthesized by microwave irradiation possessed a lower content of silica, larger dimensions of both the individual crystals and polycrystalline agglomerates, and a lower amount of strong Brönsted and Lewis acid sites. Investigation of the properties of the prepared SAPO-11 materials in a naphthalene methylation reaction revealed that all of the samples demonstrated good activity in the reaction and catalytic stability with Time-On-Stream regardless of the synthesis method used. A higher 2,6-dimethylnaphthalene/2,7-dimethylnaphthalene molar ratio was observed for SAPO-11 samples prepared by microwave irradiation, which was attributed to a milder acidity of these materials.