Hydrogen production from ethanol over silica supported cu and zn oxide catalysts

Abstract

Günümüzde en önemli enerji kayna ı fosil yakıtlarıdır fakat fosil yakıtyataklarındaki azalma ve bunların kullanımının atmosfer üzerindeki olumsuz etkisitemiz enerji konulu ara tırmalara hız kazanmı tır. Etanoldan üretilen hidrojen yakıthücrelerinde kullanıldı ında hem verimli enerji üretilmekte hem de do ada kapalıbir karbon çevrimi olu turulmaktadır.Bu çalı manın amacı etanoldan buhar riformlaması tepkimesinde yüksekperformans sa layacak katalizör tasarlamaktır. Etanol buhar riformlamasıendotermik bir tepkimedir, hidrojen ve CO2 üretilir. Silikanın üzerine farklı ZnO veCu yükleyerek katalizör sentezlenmi tir.Sentezlenen bütün katalizörler XRD ve BET analizleri ile karakterizeedilmi tir. BET analizinde, ZnO yüklemesi arttı ında yüzey alanının azaldı ıgörülmü tür. XRD analizinde de çinko silikat kristalleri görülmemi tir.Hazırlanan bütün katalizörlerin aktivite ve seçimlilik testleri dolgu yataklıreaktörde 300 ve 500oC arasında yapılmı tır. Etanolun buhar riformlamasıdeneyinde, farklı ZnO eklemelerinde, ZnO/SiO2 katalizörünün performansı ayrıca Cueklenmi katalizörlerinde performansı incelenmi tir. Bütün katalizörler için,sıcaklıkla beraber aktivitenin arttı ı gözlenmi tir.

The majority of current energy needs are supplied by combustion of non-renewable energy sources such as fossil fuels, which is associated with release of largequantities of greenhouse gases, especially carbon dioxide and other harmful emissionsto the atmosphere. The gradual depletion of these fossil fuels reserves and efforts tocombat pollution and greenhouse gas emissions have generated a considerableinterest in using alternative sources of energy. Ethanol used in the hydrogenproduction process by steam reforming.The purpose of this work was to design a high performance catalyst for theproduction of hydrogen from steam reforming of ethanol. Ethanol steam reformingreaction is an endothermic reaction of ethanol with water to produce hydrogen andcarbon dioxide. The different ZnO loading supported SiO2 catalyst and Cu promotedZnO/SiO2 catalysts were prepared single step sol-gel method with different Culoading.All catalysts were characterized by X-ray diffraction, BET surface areameasurements and pore diameter analysis. BET surface area decreased and averagepore diameter increased as the ZnO loading increased. Based on the XRD findings, itseems that zinc silicate crystallite phase is not formed under the preparationconditions used in this dissertation.The activity and selectivity tests of all catalysts were performed in a packedbed reactor with reaction temperature between 300 and 500oC. The performances ofZnO/SiO2 catalysts in ethanol steam reforming reaction were investigated as afunction of ZnO loading. Cu catalysts are known as active catalysts for ethanoldehydrogenation. As the temperature was increased, the conversion increased andreached a maximum at 500oC for all Cu loadings.