Catalytic activity of mesoporous Ga-SBA-15 materials in a-pinene isomerisation: Similarities and differences with Al-SBA-15 analogues

摘要

A complete investigation of the catalytic activity of Ga-SBA-15 materials in a-pinene isomerisation is presented here. The performances of solids with different Si/Ga ratios prepared either by grafting or direct synthesis are compared with those of Al-SBA-15 analogues. In the case of Ga samples prepared by direct synthesis, a-pinene conversion can reach 90%, in relatively mild experimental conditions (353 K, 1 h). Camphene and limonene represent more than 50% of the products formed. In the case of samples prepared by post-synthesis, a-pinene conversion decreases with the Ga content, but remains much higher than with the corresponding Al-SBA-15 materials. In this latter case, heavy compounds are the main products and can correspond to more than 50% of the isomerised a-pinene. Undeniably Ga-SBA-15 solids allow better yields of camphene + limonene and limit the production of heavy undesirable byproducts.