Preparation Of Rare Earth(La,Ce)-Silicon Composite Oxide Aerogel And Its Application As A Nickel-based Catalyst Carrier In Partial Oxidation Of Methane(POM)

Partial oxidation of methane into syngas(POM)is one of the most important ways to utilize methane.The commonly used Ni-based catalysts with a low price exhibited well catalytic properties,showing a great prospect in application.However,the catalysts are often deactivated as a result of sintering and coking upon Ni.An important way to solve this problem is to prepare a carrier which has both well structural and functional effects.In this work,a series of Ni-based catalysts(supported on rare earth(La,Ce)-silicon composite oxide aerogels)are prepared.It is expected that the advantage of structure from aerogels combined with rare earth-silicon composite enhances the catalytic properties of the catalysts in POM,and the understanding upon structure-properties relationship will be given with help of characterization on catalysts.The main results are as follows,1.Rare earth(La,Ce)-silicon composite oxide aerogels with larger specific surface area and porous structure are obtained by surface modification,multi-step solvent replacement and other methods which can effectively reduce the structural damage caused by surface tension during drying.2.The Ni-based catalysts supported on rare earth(La,Ce)-silicon composite oxide aerogels show well POM activity and stability compared to single oxide supported catalysts.The increase of the activity of catalysts is due to the enhancement of the reducibility of Ni.This is related to the weak interaction between Ni and carrier,the dispersion of the active component by the aerogel carrier,and the presence of rare earth atoms.The improvement of the stability of catalysts is due to the isolation of the Ni particles by rare earth oxides,the well oxygen storage/release properties from rare earth oxides which inhibits sintering and carbon deposition on Ni.3.The samples with a suitable Si/La ratio(0.65/1)can form a composite phase La9.33Si6O26 during POM.This phase leads to the promotion of the POM reaction and inhibition of carbon deposition on the surface.Thus,the activity and stability of the catalysts are significantly improved,and stability.While Ce-Si combination to form a composite phase within the ratio range,the related POM catalytic performance is not improved.