Application: The CDHydro catalytic distillation technology processes reformate streams from refineries to reduce benzene to levels required by low-benzene gasoline specifications.
Description: The patented CDHydro process achieves hydrogenation of benzene to cyclohexane in a catalytic distillation column. Hydrogenation reduces benzene in the gasoline pool. The process uses commercially available catalyst in proprietary catalytic distillation structures. Selective hydrogenation: Reformate and hydrogen are fed to the catalytic distillation column. Hydrogenation of benzene to cyclohexane can exceed 99%. Benzene conversion can easily be limited to lower levels through control of hydrogen addition. Washing action of the reflux minimizes oligomer formation, flushes heavy compounds from the catalyst and promotes long catalyst life. Treated C6 product is taken as overhead. Excess hydrogen and lights are recycled and vented from the overhead drum. The C7+ product is taken as bottom with essentially full recovery of heavy aromatics.
The unique catalytic distillation column combines reaction and fractionation in a single unit operation. This constant-pressure boiling system assures precise temperature control in the catalyst zone. Low reaction
temperature and isothermal operation enhance safety.
Economics: Capital costs are considerably lower than conventional hydrotreaters since the single-column design eliminates costs associated with fixed-bed systems and operates at low enough pressure to avoid the need for a hydrogen compressor. The CDHydro process would typically be installed in a benzene-toluene splitter, either as a retrofit or in a new column.
• Lower capital cost
• High conversion
• Simple operation
• Low operating pressure
• Low operating cost
• Low capital cost
• Low benzene in reformate
• All carbon steel construction
• No hydrogen compressor
• Isothermal operation
• Reduced plot area.