Acid catalyst technology

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. 

Cationic polymerization of coal-tar fractions has been commercially achieved through the use of strong protic acids, as well as various Lewis acids. Sulfuric acid was the first polymerization catalyst (11). More recent technology has focused on the Friedel-Crafts polymerization of coal fractions to yield resins with higher softening points and better color. Typical Lewis acid catalysts used in these processes are aluminum chloride, boron trifluoride, and various boron trifluoride complexes (12). Cmde feedstocks typically contain 25—75% reactive components and may be refined prior to polymerization (eg, acid or alkali treatment) to remove sulfur and other undesired components. Table 1 illustrates the typical components found in coal-tar fractions and their corresponding properties. 

Gymene. Methyhsopropylben2ene [25155-15-1] can be produced over a number of different acid catalysts by alkylation of toluene with propylene (63—66). Although the demand for cymene is much lower than for cumene, one commercial plant was started up in 1987 at the Yan Shan Petrochemical Company in the People s RepubHc of China. The operation of this plant is based on SPA technology offered by UOP for cumene. The cymene is an intermediate for the production of y -cresol (3-methylphenol) [108-59-4]. 

Some details of this new process have been pubUshed by UOP (86). UOP claims equal or better LAB product quaUty via the fixed-bed process compared with the conventional Hquid-phase process employing HP acid catalyst. The new technology requites approximately 15% lower capital investment, mosdy the result of the elimination of safety equipment and equipment related to HP acid neutralization. 

Process. As soHd acid catalysts have replaced Hquid acid catalysts, they have typically been placed in conventional fixed-bed reactors. An extension of fixed-bed reactor technology is the concept of catalytic distillation being offered by CR L (48). In catalytic distillation, the catalytic reaction and separation of products occur in the same vessel. The concept has been appHed commercially for the production of MTBE and is also being offered for the production of ethylbenzene and cumene. 

Nitric acid is one of the three major acids of the modem chemical industiy and has been known as a corrosive solvent for metals since alchemical times in the thirteenth centuiy. " " It is now invariably made by the catalytic oxidation of ammonia under conditions which promote the formation of NO rather than the thermodynamically more favoured products N2 or N2O (p. 423). The NO is then further oxidized to NO2 and the gases absorbed in water to yield a concentrated aqueous solution of the acid. The vast scale of production requires the optimization of all the reaction conditions and present-day operations are based on the intricate interaction of fundamental thermodynamics, modem catalyst technology, advanced reactor design, and chemical engineering aspects of process control (see Panel). Production in the USA alone now exceeds 7 million tonnes annually, of which the greater part is used to produce nitrates for fertilizers, explosives and other purposes (see Panel). 

BP Chemicals studied the use of chloroaluminates as acidic catalysts and solvents for aromatic hydrocarbon allcylation [41]. At present, the existing AICI3 technology (based on red oil catalyst) is still used industrially, but continues to suffer from poor catalyst separation and recycling [42]. The aim of the work was to evaluate the AlCl3-based ionic liquids, with the emphasis placed on the development of a clean... 

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. ... 

When a phosphite is used as a catalyst modifier, it is susceptible to oxidation in the same manner as a phosphine. Unlike triphenylphosphine oxide, which is relatively innocuous except for precipitation when the solubility limit is reached, phosphite oxidation products may hydrolyze to give phosphoric acid. Since phosphites are esters, phosphoric acid can catalyst additional hydrolysis. Other than limiting formation of phosphite oxidation products, the best approach is to include some acidity control technology in the separation or reaction system. 

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. 

U.S. consumption pattern 1999, 3 619t U.S. producers, 3 610t vapor-phase nitration of, 17 257 vinyl chloride reactions with, 25 632 world production by country, 3 611-612t Benzene-based catalyst technology, 15 500 Benzene-based fixed-bed process technology, 15 505-506 Benzene chlorination process, of phenol manufacture, 18 751 m-Benzenedisulfonic acid, 3 602 p-Benzenedisulfonic acid, 3 602 Benzene feedstock, 23 329 Benzene hexachloride, 3 602 Benzene manufacture, toluene in, 25 180-181... 

The Biginelli procedure is amenable to microwave technology, and several microwave-assisted procedures have now been published <2002SC147, 2004SL235>. An example is the microwave-assisted solution-phase synthesis of dihydropyrimidine C-5 amides and esters 723 using ytterbium triflate as the Lewis acid catalyst <2006T4651>. 

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. 

In the long run solid catalysts are expected to be used, which would reduce the safety problems of liquid-phase alkylations. However, much further work is needed to develop such processes,7 and their introduction will be costly. The startup of a pilot plant to demonstrate a solid acid catalyst alkylation technology jointly developed by Catalytica, Conoco, and Neste Oy has been announced.307... 

A more recent development in ethylbenzene technology is the Mobil-Badger process,161,314-316 which employs a solid acid catalyst in the heterogeneous vapor-phase reaction (400-45O C, 15-30 atm). A modified H-ZSM-5 catalyst that is regenerable greatly eliminates the common problems associated with... 

The conventional resinsulfonic acids such as sulfonated polystyrenes (Dowex-50, Amberlite IR-112, and Permutit Q) are of moderate acidity with limited thermal stability. Therefore, they can be used only to catalyze alkylation of relatively reactive aromatic compounds (like phenol) with alkenes, alcohols, and alkyl halides. Nafion-H, however, has been found to be a suitable superacid catalyst in the 110-190°C temperature range to alkylate benzene with ethylene (vide infra) 16 Furthermore, various solid acid catalysts (ZSM-5, zeolite /3, MCM-22) are applied in industrial ethylbenzene technologies in the vapor phase.177... 

BASF s original acid scavenger, triethylamine, created viscosity and work-up problems because of the need to maintain anhydrous conditions. BASF s use of 1-methylimidazole instead of triethylamine, at their reaction temperature of 80°C, led to the formation of two liquid phases, an upper diethoxyphenylphosphine phase, and a lower methylimidazolium chloride phase (fortuitously, this ionic liquid melts at 75°C ). Moreover, methylimidazolium chloride proved to be a nucleophilic catalyst. The processing revolution generated by these discoveries enabled creation of a high-productivity continuous process for diethoxyphenylphosphine manufacture and created a whole new business in acid scavenging technology. 

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