Naphtha Steam Reforming Catalyst Pre-technology Research And Development

The hydrogen production unit of Baling petroleum chemical corporation uses naphtha as raw material to gain hydrogen,adopting hydrocarbon vapor reforming techniques.Its key process is hydrocarbon vapor reforming techniques.The vapor reforming takes place inside the reformer,which is a fixed bed tube reactor.At the temperature of 780～820℃,the pressure of 2.5～2.9MPa and steam/carbon ratio of 4.5～5.5,naphtha and water vapors will carry on reforming reaction,producing H₂,CO,CO₂ and CH₄.After transformation,decarburization,methanising and pressure swing adsorption high-purity hydrogen is obtained.Apart from the reforming reaction,other reactions such as decomposition,carbon deposition,carbon disappearance and coke deposition and so on also happen inside the reformer at the same time.With the naphtha's quality going down,carbon deposit on the catalyst's surface will be more and more obvious.Once the carbon deposit becomes relatively serious,speck and red tube will appear in the reformer pipe,which will affect heat transfer efficiency and even cause the catalyst bed's resistance to rise,resulting in the explosion of reformer pipe and the halt of the equipment' work.Due to the naphtha's dry point in this equipment is 180～210℃,and the carbon deposit's trend is very obvious,the equipment's on-stream time is short,from half a year the shortest to a year the longest.This puts the corporation's safety production into a prodigious passive position.Since 1997,Baling petroleum chemical corporation,work together with Qilu Petroleum and Chemical Corporation and Luoyang Petroleum and Chemical Engineering Corp,to explore new hydrocarbon vapor pre-reforming techniques,so as to prolong the equipment's on-stream time.More than two years' efforts resulted in the successful development of new pre-reforming techniques and the outcome of the right pre-reforming catalyst in October,1999.The principle of pre-reforming reaction is,in the adiabatic and bed reactor,naphtha and water vapors will carry on pre-reforming reaction and develop methane—rich gas at the temperature of 400～480℃,the pressure of 2.5～2.9MPa and the steam/carbon ratio of 2.0～2.5.Then,methane—rich gas reenters the reformer and reacts with water vapor.Due to the essential change of the raw material gas inside the reformer, the carbon deposit's trend is going down greatly.In several years' operation,this technique has achieved enormous success.The equipment's production load has increased 40%,and the equipment's on-stream time has reached four years,which have contributed greatly to the corporation's safety production and expanding capacity.This paper introduces hydrocarbon vapor reforming,the mechanism of pre-reforming reaction,the development of pre-reforming and the exploration process of pre-reforming techniques.