To provide more acid-base active sites for catalyzing esterification and transesterification, a novel bifunctional heterogeneous catalyst was synthesized by modifying ZIF-67 with phosphotungstic acid (HPW) for biodiesel production. The proportion of coordinated Co-N bonds in ZIF-67 decreased from 32.4% to 21.7%, because they were destroyed by HPW to form coordinatively unsaturated Co cations and N⁻ extremities of imidazolate ligands. Then terminal W = O groups in HPW interacted with N⁻ extremities in ZIF-67 via covalent W-O-N bonds, which strengthened catalysts recyclability. The released coordinatively unsaturated Co cations and N⁻ extremities enhanced Lewis acid-base properties of catalysts, facilitating conversion of microalgal lipids to fatty acid methyl ester. The ratio of Lewis acid sites to Brønsted acid sites increased from 0.1 to 0.66 and Lewis base sites increased from 0.45 to 4.53 mmol/g. The conversion efficiency of 98.5% over optimum HPW-modified ZIF-67 (weight ratio = 0.25) was higher than that of 72.7% over pure ZIF67 catalyst.

为了提供更多的酸基活性位点来催化酯化和酯交换反应，通过用磷钨酸（HPW）修饰ZIF-67合成了一种新型的双功能多相催化剂，以生产生物柴油。协调CO-N键在ZIF-67的比例从32.4％下降到21.7％，因为它们是由HPW破坏以形成配位不饱和钴阳离子和N ^-咪唑配体的末端。然后终端W =在HPWö基团相互作用用N ^-在ZIF-67通过共价键WON，这加强了催化剂可回收四肢。被释放的配位不饱和有限公司阳离子和N ^-末端增强了催化剂的路易斯酸碱性质，促进了微藻类脂质向脂肪酸甲酯的转化。Lewis酸位与Brønsted酸位的比例从0.1增加到0.66，Lewis碱位从0.45增加到4.53 mmol / g。相对于最佳HPW改性的ZIF-67（重量比= 0.25），转化率为98.5％，高于纯ZIF67催化剂的转化率为72.7％。