Alkylate is an ideal clean fuel component because it has a high octane rating, low sulfur concentration and no aromatics or olefins. Alkylate is currently produced using either sulfuric or hydrofluoric acid as the catalyst. Both acids are dangerous and can lead to corrosion-induced accidents and impede firefighting efforts. Solid acids have for many years promised safer and cleaner alkylation. The short cycle-times of most solid acids, however, have resulted in expensive processes with complex reactors and large catalyst inventories, making them uncompetitive with liquid acid technology.
After years of development, a new solid-acid catalyst technology, ExSact, has reached the point of outperforming these liquid acids. The engineered solid-acid catalyst has been designed at multiple levels to give over 24-hr cycle-times, robust resistance to typical poisons such as mercaptans, diolefins and oxygenates, the ability to handle a variety of feedstocks, a simple fixed-bed reactor design and regeneration using hydrogen. The ExSact catalyst forms the core of a safe and efficient process that generates high-octane alkylate without the dangers and costs associated with liquid acid technology.
The integration of catalyst science and reaction engineering allows ExSact catalyst cycle-times that are 3000% longer than most solid-acid catalysts and produces high-octane alkylate from any olefinic source, including FCC olefins, FCC off-gas and MTBE raffinate. The stable catalyst performance greatly simplifies the overall process design, which reduces the capital cost of the alkylation plant, while lowering energy consumption.
The ExSact process alkylate yields are higher than in liquid acid systems due to elimination of acid-soluble oils (a byproduct of liquid acid systems), resulting in lower olefin feedstock consumption. The engineered catalyst system has optimally designed acid sites that produce high octane alkylate over a wide range of process conditions by minimizing product cracking and reducing product degradation. The ExSact solid acid catalyst has significant environmental and safety advantages over both hydrofluoric acid and sulfuric acid because it is neither corrosive nor hazardous to people or the environment. Investment costs are lower than liquid-acid technologies due to simpler reactor design using inexpensive materials of construction and the elimination of refrigeration equipment and acid handling vessels
ExSact is currently being licensed exclusively by KBR as the K-SAAT process.