The Preparation And Application Study On Catalyst And Separation Of ZIF-67 Composites

ZIF-67 is a type of metal-organic frameworks with three-dimensional structure, which can be synthesized by Co(NO3):·6H2O and 2-methyl imidazole as starting materials. ZIF-67 has promising applications in catalyst and gas separation with the 3.4 A of average pore size and numbers of metal active sites. However, it is hard to recycle by using ZIF as catalysts and gas seperation directly due to its powdery characteristics and weak mechanic strength.It is possible to load ZIF-67 on some supporters to impove the structural strength and easy to recylcle. In this work, n-ZIF-67@Fe3O4 (n=1,4,7,10) and n-ZIF-67@NH2-??-Al2O3 (n=3,5,7,10) were synthesized successfuLly by loading ZIF-67 on magnetic Fe3O4 and ?-Al2O3 through layer-by-layer self-assembly method. The catalytic activity and separation performance of catalysts were studied in detail.Firstly, the different loading cycles n-ZIF-67@Fe3O4 (n=1,4,7,10)magnetic core-shell structure materials were synthesized successfuLly by loading ZIF-67 on carboxylic Fe304 particles via layer-by-layer self-assembly method. The n-ZIF-67@Fe3O4 was utilized as catalyst in the catalytic reduction of nitrophenol compounds (NPs), and the influence of catalyst amount, loading cycles of ZIF-67, and reaction species on catalytic reduction were investigated. The resuLts indicated that the 4-ZIF-67@Fe304 magnetic core-shell structure material showed the best catalytic active for NPs catalytic reduction and 97.3% 4-NP can be reducted to 4-AP within 5 min with 10 mg ZIF-67@Fe3O4, at room temperature. The catalytic active order for NPs reduction is as follows:4-NP > 2-NP > 3-NP. Moreover, 4-ZIF-67@Fe3O4 can be easily recylcled by magnetic separation, and there is no obvious catalytic active decrease after 5 cycles.Secondly, different loading cycles n-ZIF-67@NH2-?-Al2O3 (n=3,5 ,7 ,10) structure materials were synthesied successfuLly by loading ZIF-67 on NH2-y-Al2O3 particles via layer-by-layer self-assembly method.n-ZIF-67@NH2-y-Al2O3 (n=3, 5 ,7 ,10) were characterized by IR, XRD,SEM, TG,ICP and BET methods. Moreover,the n-ZIF-67@NH2-y-Al2O3(n=3, 5 ,7 ,10) materials were used as gas chromatographicas stationery phase materials for H2/D2 separation. Some influence on separation effect of loading cycles, flow velocity of He, sample volume, etc. was investigated under conditions of detector temperature 100 ?, bridge current of 160 mA, and colume temperature 77K. The resuLts show that the H2/D2 isotope separation factor of 7-ZIF-67@NH2-?-Al2O3 gas chromatographic column can reach 1.79 within 6 min, respetively, under the conditions of sample volume 50 uL and flow velocity of 60 mL·min-1.Thirdly, n-ZIF-67@NH2-y-Al2O3 (n=3, 5,7,9) was also used as catalyst for Knoevenagel reaction in order to expand the further application of ZIF-67. The influence of reaction conditions on the conversion rate and selectivity of Knoevenagel reaction was studied,contained loading cycles, reaction temperature, reaction time, reagents mole ratio, solvents, ect. The best reaction conditions were confirm on loading cycles of 5, reaction temperature of 50 ?, reaction time of 240 min, reagent mole ratio of 1:1, and ethanol as solvent. As the comprehensive experimental resuLts indicated that 5-ZIF-67@NH2-y-Al2O3 has good catalytic capacity for Knoevenagel reaction and can be suitble for successive use.