Green synthesis of monododecylphosphate over MCM-22 molecular sieve modified by calcium

Ca/HMCM-22 and CaHMCM-22 zeolite catalysts were prepared by impregnation and ion exchange respectively. The catalysts were characterized by XRD, TPD, FT-IR, and ICP. When CaSO₄ loading was less than 6.5%, CaSO₄ could be highly dispersed on HMCM-22 zeolite. A few variations in the strength and content of weak acid, and a slightly decrease of the content of strong acid were found in the two catalysts. However, the strength and content of weak and strong base on CaHMCM-22 were more than those on Ca/HMCM-22 after modification. The two catalysts exhibited good catalytic performance for the synthesis of monododecylphosphate by esterification of phosphoric acid with equimolar lauryl alcohol. The catalytic activity over Ca/HMCM-22 zeolite was higher than the catalytic activities of HMCM-22 and Ca/NaMCM-22 zeolite, CaSO₄ in synergy with acid sites and base sites of zeolite catalyst accelerated the esterification. The catalytic activity over CaHMCM-22 exchanged 3 times was also better than those of HMCM-22 and CaNaMCM-22 zeolite. Combined with the results of characterization and esterification, the presence of acidic and basic sites promoted effectively the synthesis of monododecylphosphate.