Catalytic dewaxing process

Abstract

A process for making a lubricant oil of low pour point and improved oxidation stability by catalytically hydro-dewaxing a lube chargestock containing paraffin wax in a vertical column reactor having a cascade series of fixed downflow catalyst beds over dewaxing catalyst comprising acid medium pore size zeolite. The treatment is carried out by selectively hydrodewaxing paraffinic wax contained in the liquid petroleum in a first serial catalyst bed under adiabatic cracking temperature conditions while controlling adiabatic exothermal heat of reaction within a 30.degree. C. maximum excursion from the initial reaction temperature, thereby producing lighter olefinic components, recovering partially hydrodewaxed liquid petroleum from a bottom portion of the first serial catalyst bed, and redistributing said partially hydrodewaxed liquid petroleum for contact with said catalyst in at least one downstream fixed catalyst bed. The partially hydrocracked liquid petroleum is further reacted to effect endothermic hydrodewaxing concurrently with exothermic hydrogen transfer, dewaxing, hydrogenation and cyclization in the presence of hydrogen under adiabatic temperature conditions, permitting net exothermic reaction temperature to rise not more than 30.degree. C. in said downstream catalyst bed. Temperature control is maintained by injecting hydrogen quench fluid into at least one downstream catalyst bed concurrently with partially hydrodewaxed liquid petroleum to decrease reaction temperature, thereby maintaining a maximum temperature excursion of about 30.degree. C. throughout said series of fixed catalyst beds and controlling uniform hydro-dewaxing conditions to obtain high quality petroleum lubricant product.