Fluid industrial isomerization

Fixed- or packed-bed reactors refer to two-phase systems in which the reacting fluid flows through a tube filled with stationary catalyst particles or pellets (Smith, 1981). As in the case of ion-exchange and adsorption processes, fixed bed is the most frequently used operation for catalysis (Froment and Bischoff, 1990 Schmidt, 2005). Some examples in the chemical industry are steam reforming, the synthesis of sulfuric acid, ammonia, and methanol, and petroleum refining processes such as catalytic reforming, isomerization, and hydrocracking (Froment and Bischoff, 1990). 

PCBs are industrial compounds used as industrial, dielectric and heat transfer fluids, organic solvents, flame retardants, plasticizers, sealant and surface coatings. They may also be released to the atmosphere by waste incineration (Fig. 3). The worldwide production of this compound has been 1.3 million tonnes, of which 97% in the northern hemisphere [23]. The amount of chlorine atoms in the biphenyl mixtures is related to the duration and temperature of the chlorination process. The commercial mixtures were distributed under names such as Aroclor (Monsanto, USA) or Clophen (Bayer, EU). The chlorine atoms can substitute the para, meta and/or ortho positions of the biphenyls. There are 209 possible congeners. PCBs can be divided into nine isomeric groups and one decachlorobiphenyl, all with an empirical formula of C Hjo-uCln (n = 1-10) (Fig. 4). 

Trichloroethane and trichloroethylene are widely used solvents found as ingredients in many products, including typewriter correction fluid ( white-ouf), color film cleaners, insecticides, spot removers, fabric cleaning solutions, adhesives, and paint removers. They are used extensively in industry as degreasers. Trichloroethane is available in two isomeric forms, 1,1,2- and 1,1,1-, with the latter (also known as methyl chloroform) being the most common. Perchloroethylene (tetrachloroethylene) is another related solvent used widely in the dry cleaning industry. 

An inspection of the industrial use of zeolites as catalysts shows, however, that only a rather limited number of zeolite topologies are currently used in major industrial processes. Among the more important ones are ultrastable Y (USY) (FAU), rare-earth-exchanged faujasite-type (X, Y) (FAU) andZSM-5-type (MFI) zeolites in fluid catalytic cracking (FCC) of oil fractions [4] noble-metal-loaded U SY for hydroisomerization and hydrocracking of naphtha feedstocks [5] mordenite (MOR) and zeolite Omega (MAZ) -based catalysts for C4-C6 alkane isomerization [6] zeolites ZSM-23 (MTT), ZSM-35 (FER), ZSM-5 for selective oil dewaxing [7] ZSM-5, silicalite (MFI), MCM-22 (MWW), Beta-type (BEA) zeolites for aromatics alkylation to yield ethylbenzene, p-xylene. 

At the heart of a refinery are its fluid catalytic cracker and hydrocracker, which break down heavy (long) hydrocarbon chains into lighter (shorter) ones. A catalytic reformer is used to create higher octane reformate, a more valuable naphtha distillate. Isomerization and alkylation are two chemical processes designed to boost the distillate s octane rating. Refineries send their products to end users or the petrochemical industry. 

Saturated branched fatty acids, such as isostearic acid, are important intermediates in various industrial products, including lubricants, surfactants, detergents, cosmetics, biodiesel, and hydraulic fluids. Saturated branched fatty acids and their alkyl esters have important advantages over natural linear fatty acids they have an excellent oxidative stability compared to unsaturated fatty acids and have a more desirable liquidity compared to linear saturated fatty acids. Furthermore, branched saturated fatty acids show a desirable low viscosity and improved formulation flexibifity [330]. As naturally occurring branched fatty acids are rare, catalytic skeletal isomerization of common linear fatty acids is required. 

---