Hydrogen carriers

It is believed that the red phosphorus is the true reducing agent and the iodine (or iodide) functions as a hydrogen carrier. This proc ure replaces the obsolete method of heating with red phosphorus and concentrated hydriodic acid in a sealed tube. 

Ma.nufa.cture. Butyrolactone is manufactured by dehydrogenation of butanediol. The butyrolactone plant and process in Germany, as described after World War II (179), approximates the processes presendy used. The dehydrogenation was carried out with preheated butanediol vapor in a hydrogen carrier over a supported copper catalyst at 230—250°C. The yield of butyrolactone after purification by distillation was about 90%. 

The phosphides tricadrnium diphosphide [12014-28-7], Cd2P2, cadmium diphosphide [12133-44-7], CdP2, and cadmium tetraphosphide [12050-26-9], CdP, may all be prepared by indirect fusion of the elements, usually by passing phosphoms vapors, in a nitrogen or hydrogen carrier gas. 

The reduction of the sample was made at 2250 K In a flowing stream of hydrogen carrier gas ( SO cm /mln). The total pressure of the carrier gas was approximately 1 atm. The water vapor produced during the reduction was swept by the carrier gas Into an electrolytic-type (P2O5) moisture monitor and a continuous recorder trace of the water concentration as a function of time was obtained. A typical plot of the moisture content of the carrier gas as a function of time Is shown In Figure 3. The region on the left side of this figure where the moisture content... 

Figure 3. Moisture concentration (ppm H2O) in the hydrogen carrier gas as a function of time during the preparation of the plutonium sesquioxide sample by hydrogen reduction at 2250 K.

Transfer of hydrogen from one substrate to another in a coupled oxidation-reduction reaction (Figure 11-3). These dehydrogenases are specific for their substrates but often utilize common coenzymes or hydrogen carriers, eg, NAD". Since the reactions are re-... 

Methanol can be considered as a hydrogen carrier in a fuel cell. Conventionally, methanol has been reformed/shift converted to produce hydrogen. A low concentration of carbon monoxide formed during this process leads to a strong poisoning of the anode, and even after cleaning of the... 

Figure 2.7 Activity test of an uncoated fused silica capillary after deactivation with poly(phenyliaethylhydrosiloxane), (A), and before deactivation, (B). Precolunn 15 x 0.20 m I.D. coated with SE-54. Test columns 10 a x 0.20 I.D. The column tandem was programmed from 40 to I80 c at a C/min after a 1 min isothermal hold with a hydrogen carrier gas velocity of 50 cm/s. The test mixture contained 10 n-decane, Cg-NH = l-aminooctane, PY 3,5-dimethylpyrimidine, C 2 n-dodecane, - 1-amlnodecane, DMA ...

In a typical experimental arrangement, the injection block heater of the gas chromatograph is used to heat a short catalyst bed containing platinum, palladium, copper or nickel coated on a diatomaceous support. The catalyst bed can be the top portion of a packed column or a precolumn connected to a packed or open tubular column. Hydrogen carrier gas flows through the heated catalyst bed (220-350 0) and then into the column. The sam B is injected by... 

Supersonic molecular beam (SMB) mass spectrometry (SMB-MS) measures the mass spectrum of vibra-tionally cold molecules (cold El). Supersonic molecular beams [43] are formed by the co-expansion of an atmospheric pressure helium or hydrogen carrier gas, seeded with heavier sample organic molecules, through a simple pinhole (ca. 100 p,m i.d.) into a 10 5-mbar vacuum with flow-rates of 200 ml. rn in. In SMB, molecular ionisation is obtained either through improved electron impact ionisation, or through hyperthermal surface ionisation... 

Dehydrogenation activities, compared for tetralin and decalin [5,12] under the same superheated liquid-film conditions over the same Pt/C catalyst, exhibited around 3.9-63 times preference of tetralin (Table 13.3), which can certainly be ascribed to advantageous adsorption due to the a-bonding capability of its aromatic part [17-19]. It was, thus, confirmed experimentally that tetralin is superior to decalin as the organic hydrogen carrier for stationary applications in terms of rapid hydrogen supply or power density, provided that the density of fuel storage is unimportant. 

Chemical hydrogen storage (hydrogen carriers not reversible on-board) High capacities Potentially liquids Complexity (two-way infrastructure, on-board processor) Decreasing regeneration costs... 

The actual selectivity depends on the nature of the catalyst. For example, the following data were reported for n-hexane transformed over platinum and palladium supported on the same alumina 44) (pulse system, hydrogen carrier gas, T = 520°C) ... 

Under anaerobic conditions, various pathways exist for pyravate metabolism which serve to re-oxidize the reduced hydrogen carriers formed during glycolysis. The ultimate acceptor builds up as a waste product in the culture medium. The end-products of the pathways are (1) CO, ATP, and acetate (2) COj and ethanol (3) and CO2 (4) COj and 2,3-butylene glycol (5) COj, Hj, acetone, ATP, and butanol (6) succinate and (7) lactate. The pathway that occurs depends on the microorganism cultivated and the culture. 

Diastereomer ratios were determined by gas chromatography. Since the aldol adduct undergoes retroaldol reaction on the column, it must be silylated prior to injection. Approximately 5 mg of the crude adduct is filtered through a short plug of silica gel to remove any trace metals. The material is taken up into 1-2 mL of dichloromethane in a 2-raL flask or small test tube. To this solution are added 4-5 drops of N,N-diethyl-1,1,1-trimethylsilylamine and a small crystal of 4-(N,N-dimethylamino)pyridine (Note 11), The solution is stirred for 2 hr and injected directly onto the column. (Column conditions 30 m x 0.32 mm fused silica column coated with OB 5, 14 psi hydrogen carrier gas, oven temperature 235°C). 

The enantiomeric excess was determined to be >99% by capillary GLC analysis (30 ra x 32 tim WCOT column coated with Carbowax 20 M, hydrogen carrier gas, linear velocity ca. 94 cra/s, oven temperature 225°C) of the imide derived from the Mosher acid chloride. ... 

Acetic acid (CH3COOH) is one of the major components of bio-oils (up to 12 wt%). Furthermore, being non-flammable, it is a safe hydrogen carrier. Nevertheless, only a few studies have dealt with the production of hydrogen from acetic acid. 

CVD of SiC normally uses silane and a hydrocarbon as the precursor gases and a hydrogen carrier gas. The gases pass over a heated graphite susceptor that is coated by SiC or tantalum carbide (TaC). 

Mercury telluride (HgTe) was first made by vapour phase epitaxy in 1984. This preparation illustrates the use of ultraviolet radiation as the energy source for decomposition. Diethyltellurium ((C2H5)2Te) vapour in a stream of hydrogen carrier gas... 

The fifth cofactor of the PDH complex, lipoate (Fig. 16-4), has two thiol groups that can undergo reversible oxidation to a disulfide bond (—S—S—), similar to that between two Cys residues in a protein. Because of its capacity to undergo oxidation-reduction reactions, lipoate can serve both as an electron hydrogen carrier and as an acyl carrier, as we shall see. 

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