Liquid Acid Technologies

AlkyClean process are fully competitive tvith current liquid acid technologies. High quality product has been produced in an operation that has proven to be reliable and robust. Sensitivity to feedstock variation is lotv and tolerance to impurities is high. The economic competitiveness of the netv SAC process is enhanced by its low mechanical complexity and the use of common (i.e., non-proprietary) refinery process equipment. 

Parameter Modern sulfuric acid Modern HF acid AlkyClean process 

Alkylate yield Base Base Base or better 

Total installed cost, ISBL Base 85% of base 85% of base 

Total installed cost, including OSBL (regeneration facilities, and/or safety installations) Base 70% of base 50% of base 

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Other observations of this test work, with respect to key alkylate product properties, were that neither the Reid vapor pressure (RVP) nor density deviated significantly from values that would be obtained via liquid acid alkylation. Further, acid-soluble oils (ASO), formed as contaminant side products in the case of liquid acid processes, could not be detected among the reaction products in our SAC testing. Compared with the liquid acid technologies, this effect results in both lower feed consumption per unit of alkylate production and eliminates generation of a by-product that can be difficult to dispose of. 

Similarly, after blending about 30vol.% of propylene with cis-2-butene, the RON loss was less than 1 number. With H2SO4 alkylation, similar amounts of propylene would lead to a RON about 1.5 lower. Table 12.10 summarizes the estimated impact of feedstock variation on RON relative to a pure cis-2-butene feedstock for the AlkyClean process and liquid acid technologies. Based on these results, it can be concluded that our new SAC technology is less sensitive to feedstock variation regarding product quality than either liquid acid technology. 

The process flow scheme for the AlkyClean process is similar to that employed for current liquid acid technologies. As illustrated in the block flow diagram in Figure 12.12, the process consists of four main sections feedstock pretreatment (optional, depending on contaminant level), reactor system, catalyst regeneration and product distillation. 

Table 12.12 Comparison of AlkyClean process with liquid acid technologies.

Capital expenses for the new solid acid process are lower than liquid-acid technologies due to the following reasons ... 

There is a real opportunity to reduce biodiesel production costs and environmental impact by applying modem catalyst technology, which will allow increased process flexibility to incorporate the use of low-cost high-FFA feedstock, and reduce water and energy requirement. Solid catalysts such as synthetic polymeric catalysts, zeolites and superacids like sulfated zirconia and niobic acid have the strong potential to replace liquid acids, eliminating separation, corrosion and environmental problems. Lotero et al. recently published a review that elaborates the importance of solid acids for biodiesel production. ... 

This contribution is an in-depth review of chemical and technological aspects of the alkylation of isobutane with lightalkenes, focused on the mechanisms operative with both liquid and solid acid catalysts. The differences in importance of the individual mechanistic steps are discussed in terms of the physical-chemical properties of specific catalysts. The impact of important process parameters on alkylation performance is deduced from the mechanism. The established industrial processes based on the application of liquid acids and recent process developments involving solid acid catalysts are described briefly. 2004 Elsevier Inc. 

The technology and chemistry of isoalkane-alkene alkylation have been thoroughly reviewed for both liquid and solid acid catalysts (15) and for solid acid catalysts alone (16). The intention of this review is to provide an up-to-date overview of the alkylation reaction with both liquid and solid acids as catalysts. The focus is on the similarities and differences between the liquid acid catalysts on one hand and solid acid catalysts, especially zeolites, on the other. Thus, the reaction mechanism, the physical properties of the individual catalysts, and their consequences for successful operation are reviewed. The final section is an overview of existing processes and new process developments utilizing solid acids. 

This section is a review of alkylation process technology. The processes in which liquid acids are used are all mature technologies and described briefly here. Information about process developments with solid acid catalysts is also presented. 

Processes based on solid acids are not operated on an industrial scale. However, several companies are developing processes or already offering technology for licensing. The overall process scheme is similar to that of a liquid acid-based process, except for the regeneration section, which is necessary with all solid acid... 

Liquid acid-catalyzed processes are mature technologies, which are not expected to undergo dramatic changes in the near future. Solid acid-catalyzed alkylation now has been developed to a point where the technology can compete with the existing processes. Catalyst regeneration by hydrogen treatment is the method of choice in all the process developments. Some of the process developments eliminate most if not all the drawbacks of the liquid acid processes. The verdict about whether solid acid-catalyzed processes will be applied in the near future will be determined primarily by economic issues. 

Laboratory research has demonstrated that the liquid corona technology can treat a variety of wastewater contaminants such as carbon tetrachloride, metal ion chelators, and industrial dyes. The technology successfully reduced initial organic contaminant concentrations (by more than 99%) for the following contaminants after exposure to corona discharge trichloroethylene (TCE), ethylene-diamine-tetraacetic acid (EDTA), and benzoic acid. Additionally, liquid corona has demonstrated removal success with carbon tetrachloride, pentachlorophenol, and perchloroethylene. 

Technologically, the Alkylene process is a break-through. Several significant inventions were required to make it technically feasible. The development of a unique solid-acid catalyst and transport reactor by UOP allows for the potential elimination of hazardous liquid acid processes. About 1 MM gallons of hydrofluoric acid inventory could be eliminated, transport of 33 MM lbs (4 MM gallons) of hydrofluoric acid per year would be stopped, and ca. 20 MM lbs per year of other fluoride containing solids would not have to be land filled. 

Lewis and protic acids, usually AICI3 and H2SO4, are used in the liquid phase at temperatures of 40-70°C and at pressures of 5-15 atm. Phosphoric acid on kieselguhr promoted with BF3 (UOP process)309 319 is used in gas-phase alkylation (175-225°C, 30-40 atm). In addition to the large excess of benzene, propane as diluent is also used to ensure high (better than 94%) propylene conversion. This solid phosphoric acid technology accounts for 80-90% of the world s cumene production. 

MEK is also produced as a by-product in the liquid-phase oxidation of -butane to acetic acid (31—33). This route was once the most favored route to acetic acid, however, since the early 1980s the acetic acid technology of choice has become methanol carbonylation, and MEK growth by this path is doubtful. 

In 1999, Akzo Nobel (which later sold its catalyst division to Albemarle) patented a new technology for alkylating hydrocarbons based on a zeolite acid catalyst [193]. This new process, AlkyClean, was then designed by ABB Lummus and Albemarle, and a 10 barrels per stream day (BPSD) demonstration unit came online in Finland in 2002. AlkyClean produces a high-quality sulfur-free alkylate (96 octane), eliminating all the drawbacks of the liquid acid catalyst technologies. There are no add-soluble oil waste streams, the reactor operates at 50-90 °C, and the catalyst is a solid, noncorrosive material, which is easily transported and stored. 

In-situ variable temperature C NMR studies (liquid state technology) of the surface species formed by adsorption of 1-butene (and -butene) on strongly acidic catalysts LaHY,... 

The refining and petrochemical industry has seen many acid-catalyzed reactions evolve from liquid acids to solid acids, and each time the benefits were multi-fold. This is one more example of this evolution. As industry adjusts to the psychological hurdle of first-of-its-kind technology, the demise of liquid acid alkylation processes will be the cornerstone in making refining a very safe operation. 

D Amico, V. et al. (2006) The AlkyClean alkylation process - new technology eliminates liquid acids. NPRA Spring 2006 Meeting, paper AM-06-41. 

A comparison of the Exelus technology with competing liquid acid processes is presented below. We have used published data and pro-rated them (the sulfuric acid unit (7) was pro-rated from a 7,500 barrel per day (bpd) plant cost of 43.5 million while the HF plant (6) was pro-rated from a 8,800 bpd plant cost of 42.5 million) to reflect a plant capacity of 10,000 bpd. 

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