With the conversion of butanes to high-value motor fuel alkylate using the CDAlkyPlus process, NGL producers now have another route to upgrade butanes to gasoline blend stock. By using isobutylene as the sole olefin source, the CDAlkyPlus technology allows for the profitable conversion of isobutylene and isobutane into high-value motor fuel alkylate.
The patented CDAlkyPlus process is a low-temperature sulfuric acid-catalyzed alkylation process coupled with a simple olefin pretreatment step. This combination provides significant benefits over direct alkylation of isobutylene as well as other isobutylene upgrading processes such is isooctene production. Because isobutane and isobutylene are incorporated together to produce a high-value alkylate product, the CDAlkyPlus process produces two times the volume of gasoline blendstock compared with isooctene production. This process is ideal for use downstream of an isobutane dehydrogentation process. The whole dehydrogenation unit product, a roughly 50/50 blend of isobutane and isobutylene, is fed directly to the CDAlkyPlus process.
This technology also provides a unique opportunity for revamping an existing dehydrogenation unit-based methyl tertiary butyl ether (MTBE) plant to produce alkylate. Much of the existing MTBE equipment can be used in the CDAlkyPlus process, thus reducing capital requirements. For these retrofit cases, the isobutane recycle around the dehydrogenation unit is essentially eliminated. This means the nbutane capacity of the complex can be doubled without expanding the existing dehydrogenation unit.
Process advantages: The benefits of CDAlkyPlus process:
Compared to direct alkylation of isobutylene
• Lower acid consumption
• Compressor horsepower requirements reduced by 50%
• Lower utilities
• No caustic waste streams
• Higher octane alkylate product
• Lower vapor pressure product.
Compared to iso-octene product alternative
• Twice the product volume.