Converted starches hydrogenation

Lay, J. J. 2000. Modeling and optimization of anaerobic digested sludge converting starch to hydrogen. Biotech. Bioeng. 68, 269-278. 

APR [Aqueous Phase Reforming] A general name for aqueous processes that convert starches, sugars, and lignocellulosic biomass into hydrogen and hydrocarbons. Developed by R.D. Cortright and J.A. Dumesic at... 

The filtrate was adjusted to a pH of 9 by adding concentrated ammonia, and than a 1 N aqueous iodine-potassium iodide solution was added dropwise, whereby the tetrahydro-pyrimido-[5,4-d] pyrimidine obtained by hydrogenation with zinc in formic acid was converted by oxidation into 2,6-bis-(diethanolamino)-8-piperidino-pyrimido-[5/4-d]-pyrimidine. The completion of the oxidation was checked by means of a starch solution. The major amount of the oxidation product already separated out as a deep yellow crystalline precipitate during the addition of the iodine solution. After the oxidation reaction was complete, the reaction mixture was allowed to stand for a short period of time, and than the precipitate was separated by vacuum filtration, washed with water and dried. It had a malting point of 157°C to 158°C. The yield was 8.0 g, which corresponds to 95% theory. 

There are several examples of one-pot reactions with bifunctional catalysts. Thus, using a bifunctional Ru/HY catalyst, water solutions of corn starch (25 wt.%) have been hydrolyzed on acidic sites of the Y-type zeolite, and glucose formed transiently was hydrogenated on ruthenium to a mixture of sorbitol (96%), mannitol (1%), and xylitol (2%) [68]. Similarly a one-pot process for the hydrolysis and hydrogenation of inulin to sorbitol and mannitol has been achieved with Ru/C catalysts where the carbon support was preoxidized to generate acidic sites [69]. Ribeiro and Schuchardt [70] have succeeded in converting fructose into furan-2,5-dicarboxylic acid with 99% selectivity at 72% conversion in a one-pot reaction... 

The glow electrolysis technique (electrolysis with an anode immersed in the solution and the cathode above the surface) at 600-800 V dc and 300-500 mA converts a solution of starch into ethylene, methane, hydrogen, and both carbon mono- and dioxides.323 Electrochemical methods for converting polysaccharides and other biomass-derived materials have been reviewed briefly by Baizer.324 These methods are mainly oxidations along a potential gradient, which decreases the activation energy of the reactants. Starch in 5 M NaOH solution is oxidized on platinum electrodes to carboxylic acids with an activation energy of about 10 kcal/mol. In acidic media oxidation takes place at C-l followed by decarboxylation and oxidation at the C-2 and C-6 atoms.325... 

The quantity of acid used is usually in the neighborhood of 16 lbs of hydrogen chloride per 2,500 gallons (0.77 g per liter) of starch slurry, producing a pH of 1.80 for the suspension. The time required to attain a desired, exact degree of conversion depends on the pH attained in the converter, which, in turn, is affected by small variations in the impurities in the starch. It is difficult to judge this effect precisely by measurement of the pH of the starch-acid mixture before it enters the converters. 

Acid catalysts other than sulfuric acid have been tested with acetic anhydride for use in starch acetylation. None of these, however, seem to exert as powerful a catalytic action as sulfuric acid, and some, particularly the halogen acids, cause even more extensive depolymerization of the starch. For example, acetic anhydride saturated with hydrogen chloride rapidly dissolves starch and converts it to low molec-... 

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