The effect of P/Ta ratio on sorbitol dehydration over modified tantalum oxide by phosphoric acid

•Phosphoric acid modification could significantly improve the activity of Ta2O5.•Isosorbide selectivity over 0.8P/TaO was improved from 3.8 to 48.3%.•The catalytic performance was mainly promoted by the P-OH species in TaH(PO4)2.

A series of modified hydrated tantalum oxides (Ta2O5·nH2O) with various contents of phosphoric acid were prepared and firstly used as the catalysts for sorbitol dehydration to isosorbide. The catalytic performance of Ta2O5 was improved significantly after modification, and the isosorbide selectivity over 0.8P/TaO was improved from 3.8 to 48.3% with nearly 100% sorbitol conversion. Characterization with NH3-TPD, FT-IR, Raman and XRD demonstrated that the introduction of phosphate has transformed Ta2O5 into two kinds of new crystalline phases exhibiting various surface acidities. The P-OH species in TaH(PO4)2 were mainly responsible for the promotion of catalytic performance over modified oxides.