Modification of Acidity of USY with Citric Acid for Oligomerization of Internal Olefin

The oligomerization performance of internal olefin strongly depends on the acid properties of solid acid catalysts. In this work, citric acid solution was used to modify USY molecular sieve. By adjusting the distribution of Al species in the molecular sieve framework, the acid type, density, and strength could be modified. Meanwhile, the meso-microstructure of porosity of USY was further optimized, which facilitated the effective diffusion of reactants and product molecules, thereby preventing excessive polymerization. The oligomerization of 2-methyl-2-butene catalyzed by modified USY molecular sieve was investigated. The experimental results showed that the USY sample treated with citric acid solution exhibited good catalytic performance under the reaction conditions of 120 ℃ and 1.45 MPa. The conversion rate of 2-methyl-2-butene reached 85.76%, which was nearly 20 percentage points higher than that of the unmodified catalyst sample.