Research On The Production Of Hydrogen Peroxide From Carbon Monoxide, Water And Oxygen Catalyzed By Amorphous NiP(B)/Al₂O₃

The amorphous NiP(B)/Al2O3 had been applied in the synthesis of H2O2 from CO, water and oxygen. It was prepared by three steps: at first, NiB/ Al2O3 was prepared by the reduction of the Ni2+/Al2O3 by KBH4 in the solution of ethanol and water; then NiP was coated on the surface of NiB/Al2O3 in the plating solution containing Ni(CH3OO)2 and NaH2PO2; at last, it was treated at a temperature of 90 – 180 ℃ for about 10 hours.The preparation of the catalysts was studied in details on the plating temperature, the composition of the plating solution, the initial pH value of the plating solution, the loads of NiP,the modification of the doped La, Ce and Co elements and the temperature of catalysts heat treatment,which significantly influenced the activities of the catalysts. In the plating temperature range of 20 to 80 ℃, the electroless plating velocity speeds up with the plating temperature increasing, the granules of the active NiP(B) alloy made at higher plating temperature is smaller than that made at lower plating temperature and the relevant catalyst had the better catalytic activity; Ni2+ can be reduced much completely with the ratio of NaH2PO2 and Ni(CH3OO)2 ascending, the catalysts showed good activity when the ratio of NaH2PO2 and Ni(CH3OO)2 is larger than 5; the pH value of the plating solution can affect the content of P element at the NiP layer, the catalysts showed the good catalytic activity when the pH value of the plating solution are in the range of 5.1~5.4; the proper load of NiP can make the catalyst stable, and the catalyst has a good activity; the doped La, Ce and Co can not improve the stability of catalyst; the heat treatment can raise the stability and catalytic activity of the NiP(B)/Al2O3 catalyst, but the higher drying temperature made the amorphous NiP(B) alloy on the surface of catalyst micro-crystallization, and the catalytic activity of the catalyst declined. XRD, SEM and XPS characterizations indicated that the catalysts had amorphous structure, the asymmetrical surface morphology and NiP(B) alloy is the surface active component. Comparing granular NiP(B)/Al2O3 catalyst with pellet NiP(B)/Al2O3 catalyst, SEM , XPS and the catalytic activity gave the evidences that the NiP(B) alloy broke off from the support which mainly leads to the deactivation of the pulverous catalyst.The NiP(B)/Al2O3 had better catalytic activity and longer lifetime than NiB/ Al2O3. The H2O2 production rate over NiP(B)/Al2O3 catalyst reaches 0.228 mmol/(g·h), which is higher than the reported results, for example, the maximum rate of 0.1 mmol/ (g·h) over noble catalysts (5% Pd/CaCO3 and 1% Ru/graphite) and the maximal rate of 0.07 mmol/ (g·h) over Ni-La-B/Al2O3 catalyst.