Application: To process C5 streams from refineries to produce a stream with high isoamylenes content that is essentially free of diolefins. The treated C5 stream is suitable for tertiary amyl methyl ether (TAME) production or alkylation feed.
Description: The patented C5 CDHydro process achieves selective hydrogenates diolefins to amylenes in a catalytic distillation column. Selective hydrogenation is a required pretreatment step for TAME production and C5 alkylation, improving product quality in both, and reducing acid consumption in the latter.
The process uses commercially available catalyst in proprietary catalytic distillation structures. 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 selectivity and minimize yield losses to paraffins. Non-reactive 3-methyl butene-1 is isomerized to reactive 2-methyl butene-2, which increases potential TAME production. Pentene-1 is isomerized to pentene-2, which improves octane number.
Refinery C5 streams are combined with hydrogen in the catalytic column. Treated C5 products are taken overhead. The washing action of the reflux minimizes oligomer formation, flushing heavy compounds from the catalyst and promoting long catalyst life. The catalyst will react acidic sulfur compounds with diolefins to form heavy compounds, which exit in the tower bottoms. The distillate product is essentially mercaptansulfur-free.
Economics: Capital costs are considerably lower than conventional hydrotreaters since the single column design eliminates costs associated with fixed-bed systems. Additionally, the ability to remove acidic sulfur compounds eliminates the need for sweetening. The C5 CDHydro process would typically be installed in a depentanizer, either as a retrofit or in a new column.
Process advantages include:
• Low operating pressure
• Low operating cost
• High product yield (low paraffin make)
• No polymer recycle across catalyst
• No sweetening required
• Essentially mercaptan sulfur-free distillate product
• Flexible butene-1/butene-2 ratio
• Retrofit to existing C4 columns
• All carbon steel construction
• Isomerization option
• No hydrogen compressor.