Studies On Optimization Of Catalysts For Hydrogen Production From Partial Oxidation And Reforming Of DME

Dimethyl Ether（DME）is inert, non-toxic and non-corrosive. Recently it was recognizedas an ideal hydrogen carrier due to its high hydrogen containing. DME production is gettingmatured, it is, therefore, promising to produce hydrogen from DME. The previous studieswere focused on the screening of the catalyst and optimization of the reaction conditions.There is little work on the optimization of the catalyst for partial oxidation and reforming ofDME.In this work, the optimization of the reforming catalyst for hydrogen production frompartial oxidation and reforming of DME was carried out, based on the study of reactionprocess and roles of catalysts. The alkaline earth metal modification of Ni/Al2O3, the normalreforming catalyst, was studied. And the Ni-based catalyst with different supports, such asCe-Zr-Ox with different Ce:Zr ratios, and mesoporous Al2O3, or MgO-Al2O3, were alsoconsidered.Among the alkaline earth metals (Mg, Ca, Sr, Ba) modified Ni/Al2O3catalysts, Mgmodified catalytic increased the crystallization and stability of NiAl2O4. Only small amount ofNi was generated in the reducing process, and tended to form nanoparticles with high activityand good stability. Mg modified catalyst, therefore, shows better catalytic performance thanthe unmodified one. On the other hand, Ca, Sr, Ba modified catalyst show worse performancethan the unmodified one, because the stability of NiAl2O4was not promoted and much moreNi was generated to form large particles.Investigation on the amount of MgO indicates that7.5%MgO and10%MgO modifiedNi/Al2O3catalysts can improve the catalytic performance. And the stability of NiAl2O4in the7.5%MgO modified Ni/Al2O3catalysts was not too high or low, a suitable amount of Ni wasgenerated in the reducing process. Therefore,7.5%MgO gives more obvious effect of themodification.The performance of Ni/Ce-Zr-Ox with different Ce:Zr ratios is better than that ofNi/Al2O3catalyst. And the Ni/Ce-Zr-Ox with Ce:Zr=1:4gives the best performance. Thegood crystallized cerium zirconium solid solution is formed in Ce-Zr-Ox with Ce:Zr=1:4. TheNiO particle gets smaller, and cerium zirconium solid solution can enhance the activity andstability of catalyst because of the unique redox properties of the solid solution whichimproves the dispersion of the active component NiO.Multi-atomic active centers are easy to be formed at low temperature in the reductionprocess for all the Ni-based mesoporous catalyst, named Ni/meso-Al2O3,meso-Ni-7.5%MgO-Al2O3and Ni/meso-7.5%MgO-Al2O3. As a result, the hydrogen yield orselectivity of carbon-containing products, is not as good as that of Ni/Al2O3catalyst.At last, the performance of7.5%MgO modified Ni/Al2O3is better than that ofNi/Ce-Zr-Ox (Ce:Zr=1:4), when comparison was executed.