Alkylation is an important refining process that produces valuable molecules, known as alkylates, which are blended with gasoline to meet minimum octane ratings in consumer markets. Alkylate makes an excellent gasoline blending stock because it burns clean, is non-toxic, has low sulfur content and exceptional antiknock properties, and has an inherently high octane rating.
The demand for alkylate gasoline has been steadily increasing and is led by growth in the consumer base, increased use of premium gasolines to power high performance engines, as well as changing regulatory standards. These changing regulatory standards are particularly aimed at increasing fuel economy and cutting harmful pollutants from vehicle emissions.
Traditional alkylation processes require the presence of strong acids such as hydrofluoric acid and concentrated sulfuric acid as catalyst, and these corrosive catalysts pose serious risks to public safety and the environment. For example, hydrofluoric acid is highly toxic and its leakage can form aerosols that are lethal to biological life. Conversely, the treatment of spent concentrated sulfuric acid has significant environmental impact from wastewater and emissions production perspectives.
For decades, the costs and risks associated with using hydrofluoric acid and concentrated sulfuric acid in the refinery have been accepted and mitigated. However, aging process equipment (some in excess of 60 years of operation) and a shift towards implementing inherently safe processes are driving refiners towards newer technologies that outperform the traditional methods on health, safety, and environmental metrics.
Regulatory and Safety Factors
Regulators around the world are well accustomed to mandating changes in the interest of public safety. Alternative high octane blending stocks such as tetraethyl lead and methyl tertiary-butyl ether have been banned since the mid 1990’s and early 2000’s over concerns of air, soil, and groundwater contamination.
In 2016, the South Coast Air Quality Management District (SCAQMD) of California published an alkylation technology study that examined the risks associated with hydrofluoric acid and concentrated sulfuric acid. In response to this study, the SCAQMD praised novel alkylation technologies in their ability to mitigate “safety concerns related to volatile acid vapor clouds and acid transportation”.
China’s Environmental Protection Agency recently implemented a policy that seeks to impose heavy penalties on operators who engage or are complicit in industrial safety violations. This has prompted many refinery owners and managers to carefully consider the inherent risks associated with their operations and quickly adopt alternative and safer technologies that can be applied throughout their operations.
Innovation in Alkylation Technology: Ionikylation
Ionikylation is a commercially proven, non-hazardous, and environmentally friendly alkylation process that is licensed by Well. Ionikylation uses a proprietary composite ionic liquid as the catalyst and produces alkylates with qualities that meet or exceed those produced using alternative means. Due to the non-corrosive nature of the Ionikylation catalyst, process equipment can be manufactured using low cost carbon steel, as opposed to stainless steel and other exotic metallurgies required by traditional alkylation processes. The Ionikylation catalyst is regenerated within the process, and a small volume of chemically benign matters and solids are ejected, which can be disposed of in a safe and responsible manner. Ionikylation is an inherently safe technology that dramatically reduces the costs and risks associated with a refiner’s operations.
Ionikylation Block Flow Diagram
Ionikylation was first piloted in 2003 in a 20 tpy operation. In 2005, the Ionikylation catalyst was successfully used to retrofit an existing 65,000 tpy sulfuric acid alkylation unit. In 2013, the world's first greenfield Ionikylation unit was commissioned, having a capacity of 100,000 tpy. Refiners in Asia-Pacific have since embraced the technology for its safety and environmental benefits: by 2020, ten new Ionikylation units will be constructed and commissioned, predominantly by state-owned refiners, with capacities ranging from 50,000 to 300,000 tpy.
Update: as of 2019Q1, three of the ten planned Ionikylation units have been successfully commissioned.
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