(136e) Solid Acid Catalyzed Alkylation of Isobutane with Butenes

Alkylate (primarily a mixture of iso-octane isomers) has been blended into gasoline for decades to improve octane and thus the antiknock properties of gasoline. Alkylate is currently made using as catalyst either HF or H2SO4. Research on developing a viable solid-acid catalyst to replace HF/H2SO4 technologies for isobutane alkylation has been ongoing since the 1970's and a large body of work has been published. Although virtually every known solid acid has been screened for its alkylation activity, solid-acid catalyzed isobutane alkylation is not commercially practiced today as the solid-acid catalysts deactivate rapidly as a result of coke buildup.

We have developed a new breakthrough alkylation process using a solid-acid catalyst and have proven out in a pilot-plant over an extended length of time using an MTBE raffinate feed. Through a combination of catalysis and reaction engineering considerations, ranging from optimization of the catalyst properties to shielding of active sites from excessively large olefin concentrations, we have engineered solid-acid catalysts with lifetimes that are an order of magnitude longer than most solid-acid catalysts. The stable catalyst performance greatly simplifies the overall process design, which reduces the capital cost of the alkylation plant, while lowering energy consumption.

The new process is expected to reduce both capital expenses (30%) and operating costs (3c/gallon) over a conventional liquid acid alkylation process, since it uses simple fixed-bed reactor designs and allows a large reduction in utility consumption by eliminating the need for refrigeration. The alkylate octane rating (RON & MON) exceeds that produced by conventional liquid acid processes by over 3 octane points under similar operating conditions.