Features of the Isobutane Alkylation with Butylenes on Zeolite Catalysts

Abstract

Isobutane alkylation with olefins is an important process to produce a high-octane component of gasoline (alkylate) obtained using mineral acids as catalysts. Solid catalysts based on zeolites are a promising alternative to acids, but their rapid deactivation makes it difficult to implement the technology on an industrial scale. In this work, we investigated the CaLaHPtX catalyst based on molded NaX zeoliste. Physicochemical analysis of the catalyst (the residual concentration of Na2O is less than 1 wt %, acidity 1452 μmol of NH3/g, and IR-Fourier spectroscopy data with the presence of bridging OH-groups at aluminum atoms with absorption bands at 3657 and 3603 cm–1) suggest good catalytic properties. Alkylation of isobutane with butylenes was carried out on a pilot plant according to a new principle - in a “structured” mode, which guarantees a high isobutane/butylenes ratio in the reaction zone. Under these conditions, the catalyst operates for at least 24 h with stable performance (butylenes conversion – 97.1 wt %, alkylate yield – 94.1 wt %, selectivity to trimethylpentanes – 76.4 wt %). It was shown that before the catalyst is regenerated, it is necessary to stop the reaction before its activity begins to decrease in order to exclude the accumulation of hard-to-desorb deposits on its surface. The combination of alkylation in the “structured” mode and the CaLaHPtX catalyst promote a long-term reaction without reducing the quality of the alkylate for at least 5 cycles of reaction - reductive regeneration - reaction.