Refinery catalysts thermal cracking

Commercial catalysts. Two commercial catalysts made by Katalistiks b.v. were used. The first, EKZ-, was steam aged at 750 C for 18 hrs prior to use and the second, an EKZ-2 equilibrium catalyst from a European refinery, was heated at 300°C in air for 3 hrs prior to use. Alpha alumina, heated at 300 0 in air for 3 hrs, was used in order to estimate the contribution to conversion from thermal cracking. 

The liquid product obtained from thermal cracking can be either catalytically cracked/ hydrocracked or co-processed with a refinery feed. Since the catalytic cracking of oil derived from MWP is more or less problematic, any cracking catalyst can be applied to oil derived from pyrolysis of plastics. But the yield and the quality of gasohne obtained from cracking step vary with the type of catalyst and the properties of the pyrolytic oil derivated from waste plastics. 

In many refineries thermal cracking processes are used to convert residues into lighter products. Low value petroleum coke is a product from the more severe cracking processes. The H-Oil process made it possible to convert the asphaltenic carbonizable portion of the residue to higher value liquid products rather than coke. In the H-Oil process an ebullated bed of catalyst is used to convert lower value heavy oil into upgraded higher value products in the presence of hydrogen. The ebullated bed reactor is an expanded bed of catalyst maintained in constant motion by the upward flow of liquid. The reactor behaves as a well mixed continuously stirred tank reactor. 

Today, the majority of ethylene is produced by thermal cracking of hydrocarbon feedstocks ranging fi-om ethane to heavy vacuum gas oils. Over 60% of the world s propylene is produced as a by-product of thermal cracking, with the balance being supplied from refinery sources and others. Raw materials are mosdy natural gas condensate components (principally ethane and propane) in the US and Mideast and naphtha in Europe and Asia. Alkanes/olefins are broken apart at high temperatures, often in the presence of a zeolite catalyst, to produce a mixture of primarily aliphatic alkenes and lower molecular weight alkanes. The mixture is feedstock and temperature dependent and separated by fractional distillation. 

---