Synthesis and characterization of 12-tungstophosphoric acid intercalated layered double hydroxides and their application as esterification catalysts for deacidification of crude oil

12-tungstophosphoric acid (HPW) intercalated LDH with the d003 value of 1.05 nm were synthesized, in which HPW may graft with the vacancies in the layer and orient in the interlayer with the C2 axis perpendicular to the layers. This phase is proved to be neither heteropolyacid salts nor polytungstate intercalated LDH as reported in most literature. Moreover, HPW intercalated LDH show better esterification activity for ethylene glycol and naphthenic acids in crude oil than their nitrate LDH precursors, due to the enhanced acidity. They may act as interlayer catalytic reactors to improve the activity.119