Hydrocarbons from glucose

The SMB technology was developed by UOP and its major field of application is in the area of binary separations. For example, SMB has been used in the chemical industry for several separations known as SORBEX processes [1-3], which include, among others, the PAREX process for p-xylene separation from a Cs aromatic fraction [4], the OLEX process for the separation of olefins from paraffins, the SAREX process to separate fructose from glucose [4] and the MOLEX process [5]. Simulated moving bed is being used particularly for separation of enantiomers from racemic mixtures or from the products of enantioselective synthesis [6,7]. It has been used for the production of fine chemicals, and petrochemical intermediates, such as Cg-hydrocarbons [8], food chemistry such as fatty acids [2], or certain sugars from carbohydrate mixtures [8] and protein desalination [9]. 

To harness the energy from glucose, cells must break the bonds in which the energy is stored. The net exothermic reaction that takes place when the bonds in glucose are broken is similar to the combustion of hydrocarbons. 

Sorbex configuration) utilizes a 5A zeolite adsorbent and light naphtha as desorbent for the separation of linear and branched chain paraffins. Olefins may be separated from saturated hydrocarbon isomers by the Olex process using CaX zeolite as adsorbent and heavy naphtha as desorbent. Separation of fructose from glucose is achieved in the Sarex process using CaY zeolite as adsorbent and water as desorbent. All of these processes are summarized in Table 5.1. 

As noted above, all vitamin is produced by microbial fermentation. A partial Hst of microorganisms that synthesize vitamin B 2 under appropriate conditions follows. Most strains, in their wild state, produce less than 10 mg/L vitamin although a few approach 40 mg/L. The organisms are both aerobes and anaerobes. The carbon requirements in the fermentations are satisfied from sources as wide ranging as hydrocarbons, methanol, and glucose. 

Whereas catabolism is fundamentally an oxidative process, anabolism is, by its contrasting nature, reductive. The biosynthesis of the complex constituents of the cell begins at the level of intermediates derived from the degradative pathways of catabolism or, less commonly, biosynthesis begins with oxidized substances available in the inanimate environment, such as carbon dioxide. When the hydrocarbon chains of fatty acids are assembled from acetyl-CoA units, activated hydrogens are needed to reduce the carbonyl (C=0) carbon of acetyl-CoA into a —CHg— at every other position along the chain. When glucose is... 

Carbon dioxide and water are the major waste products from most natural and industrial processes and hence are found in large quantities in the environment. If an efficient and cheap means could be found, the reduction of C02 could provide a potentially rich source of carbon for utilisation in the production of, for example, synthetic hydrocarbon fuels to replace petroleum, formic and oxalic acids for the chemical industries and foodstuffs such as glucose. 

Alkyl polyglycosides have long been known but only now, following several years research, has it been possible to develop reaction conditions that allow manufacture on a commercial scale. The structure on which these compounds are based corresponds exactly to the surfactant model described above. The hydro-phobic (or lipophilic) hydrocarbon chain is formed by a fatty alcohol (dodecanol/ tetradecanol) obtained from palm kernel oil or coconut oil. The hydrophilic part of the molecule is based on glucose (dextrose) obtained from starch (Fig. 4.14). 

The procedure towards an environmentally benign process starts with the selection of raw materials in addition to conventional raw materials from the petrochemical industry based on low- to medium-boiling aliphatic and aromatic hydrocarbons, replenishable raw materials from nature are increasingly available nowadays. In the simplest cases, these can be carbon sources, such as glucose and sucrose for fermentation, but also more complex molecules, frequently obtained from the chiral pool or through inexpensive fermentation from carbon sources, such as glutamic acid or citric acid. Table 20.2 lists a selection of raw materials from the chiral pool, with their estimated costs per kilogram. 

Riboflavin is produced by Clostridium, Ascomycetes and Candida species. The yield can be as high as 5 g 1 1 after 7 days 60). Gibberella fujikuroi is utilized for the synthesis of gibberellins, a group of plant hormones used for plant growth promotion. Glucose, molasses, lipid (corn oil) are usually used as carbon sources. Vitamin B12 may also be synthesized from alcohols and hydrocarbons. 

There is water vapour in the air, as can be seen on a cold day when it condenses out of the air of a room onto the window panes of a house (unless they are double or triple glazed), or are even seen as we breathe out. Water vapour comes from any process of burning a hydrocarbon in oxygen, and that includes us as we burn up glucose in our bodies to produce energy plus the waste gases of C02 and H20. Our metabolic processes also produce water and water vapour, which we exhale in our breath. Plants do a similar thing. Cars, when they burn petrol, and power stations as they burn oil, gas or coal all produce water vapour. 

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