Preparation Of Aluminum Phosphate Molecular Sieves And Their Application To Preferential Oxidation Of CO To H₂-rich Gases

CO preferential oxidation (CO-PROX) is a way to remove CO byoxidation.CO-PROX is considered as one of the most effective and easiest method toreduce CO c in H2-rich gas to ppm levels. Molecular-sieve catalysts carried catalystsgenerally show a good performance in the PROX reaction, such as: Pt/mordenite,Pt/3A, Pt/YSZ... In the literature[1,2]the author summarized the performances of themolecular-sieve carriers in decreasing order as follows: A-type zeolite> mordenite>X-type zeolite> alumina. However, Aluminophosphate molecular sieves in theapplication of carbon monoxide preferential oxidation have not been reported. Basedon this conception, we used the impregnation method to prepare a series ofPt-Me/MeAPO-5catalysts for research.We prepared a series of heteroatom’s Aluminophosphate molecular sieves(CoAPO-5FeAPO-5; NiAPO-5; MnAPO-5; CuAPO-5) and made characterizationand activity test. The results showed that the heteroatom metal ions could be dopedinto the Aluminophosphate molecular sieves without destroy the structure. ThroughUv-Vis spectroscopy characterization, we could see the change of the metal valence.But combined with TPR results and we can see that the Aluminophosphate molecularsieves could not show an obvious redox property.A series Pt-Me/MeAPO-5has been prepared. we investigated the effect ofdifferent Pt/Me mole ratio, different kinds of metal（Me=Co，Cu，Fe，Mn，Ni） onthe properties of catalyst in CO PROX. the results showed that the activity changed alot with the varies of the Me. We found that Cu, Mn ions had negative effect on theactivity of catalysts, Ni ions showed little change, the Fe and Co ions had a positiveeffect on the activity of catalyst. As the Pt/Me mole ratios changes, we could see thefurther changes in the performance of catalysts. The Pt-Co/CoAPO-5catalyst showedthe most excellent performance in the CO-PROX reaction among thePt-Me/MeAPO-5catalysts.We further prepared a series of Pt-Co/CoAPO-5catalysts and studied those indetail. We optimized the ultrasonic time, preprocessing temperature, calcinationtemperature, and Pt/Me mole ratio, heteroatom doping factors to achieve the bestCO-PROX activity. finally, the activity of Pt2Co/CoAPO-5catalysts could get over 99.9%conversion at65°C-110°C.And the activity of the Pt2Co/CoAPO-5catalystscould maintain for over40h under ideal atmosphere.CoAPO-5can further improvethe catalytic activity for that the CoAPO-5can weaken the interaction of promotion ofcobalt oxide with Pt-Co alloy interaction. Making O-ions easier to overflow from thecobalt oxide towards the Pt particle surface, and then react with the CO moleculesadsorbed on the Pt surface.We tried to prepare monolithic Aluminumphosphate molecular sieves. The XRDand optical images proved that the monolithic Aluminumphosphate molecular sievematerial is made. But at the same time, we found that the mechanical strength wasvery poor. The mechanical strength need to be further improved.