Stoichiometric yield

Figure 3. Numerical integration of Equation E2 showing net oxidant [03-N0 ] yields from an initial [NMHCJq = SOOppb. A. Variation with the product reactivity parameter Q here a=)9=l and S=l. B. Variation with the dilution parameter S here a=)9=l, Q=l. When S is small, a nearly stoichiometric yield of oxidant=1000ppb is achieved at higher values of S, oxidant and reactants are diluted with less oxidant accumulation.

Of these reactions, 1 and 2 gave high stoichiometric yields of 75% and 95%, reaction 4 of only 2.5%. The other two reaction yields were in the region of the detection limit. 

Table 10 Composition, molecular weight, stoichiometric air-to-fuel ratio (s), net heat of complete combustion (Ahcj), and maximum possible stoichiometric yields of major products (yi max) for ordinary polymers... 

Table 6.1 lists the stoichiometric yields of hydrogen and percentage yields by weight from steam reforming of some representative model compounds present in biomass pyrolysis oils, and also several biomass and related materials. The table also shows the equilibrium yield of H2, as a percentage of the stoichiometric yield, predicted by thermodynamic calculations at 750 °C and vdth a steam-to-carbon (S/C) ratio of 5 [32]. 

Table 6.1 Stoichiometric yields of hydrogen from complete steam reforming reactions (adapted from Ref [34]).

The stoichiometric yield of OH0 is the greatest from the photolysis of hydrogen peroxide. But - as already mentioned - the photolysis of ozone yields more OH0 than that from hydrogen peroxide because of the higher molar extinction coefficient of ozone compared to hydrogen peroxide (see Table 2-3). 

Triose phosphate isomerase, TIM, as a nearly-diffusion-limited enzyme (Ch. 2, Section 2.2.3), catalyzes the equilibration of GAP and DHAP very efficiently. However, equilibrium concentrations of GAP were metabolized to pyruvate and further to ethanol or acetate, so the stoichiometric yield on glucose to 1,3-PPD of 42.5% was lower than the target of 50%. Thus, TIM was cloned out to prevent equilibration between the desired DHAP and the undesired side-product GAP, which successfully increased the yield beyond the minimum target... 

In an attempt to understand the fundamental hydronation chemistry of bridged N2 complexes, we developed the system based on [ M(S2CNEt2)3 2(li-N2)] (M = Nb or Ta, the same group of the Periodic Table of the Elements as V). These systems have the advantages that they react with an excess of acid to give stoichiometric yields of N2H4, and the reactants and products have been... 

Shown in Figure 10, this ammonia plant is a major part of the overall fertilizer site complex. Other major facilities include urea plant, steam system, and cooling water system. Most of the ammonia is used to make granulated urea product. The other raw material for urea synthesis is C02 from the C02 capture system in the ammonia plant, supplemented with a small stream from an adjacent business. The ammonia production and the C02 available from the ammonia plant are never precisely in balance, in part because of the overall stoichiometric yields of ammonia and C02 from the natural gas feedstock. C02 is the limiting feedstock for the urea plant and its production rate in the ammonia plant sets the urea plant production rate since there is no intermediate C02 storage to buffer the urea production from the C02 production rate. Ammonia that is produced in excess of that which is used to make urea... 

Several of the terms above have been discussed in Sec. 7 rg and r are the specific rates (per broth volume) for cell growth and death, respectively rsm is the specific rate of substrate consumed for cell maintenance, and are the stoichiometric yield coefficient of species i relative to biomass x. The maintenance term in Eq. (19-81) can result... 

Stoichiometric yield RY is defined as the ratio of the actual product to the theoretical amount that may be obtained from the reference reactant ... 

This measure considers always an ideal process, but in contrast with the stoichiometric yield, takes into account the quantitative contribution of other molecules. For this reason it is equivalent to an atomic utilization . This parameter is constant over a synthesis route and as a result a measure of material utilization. Thus, it is the maximum productivity to be expected. A lower BA, value means more waste in intermediate synthesis steps and a signal to improve the chemistry, by fewer intermediate steps or better selectivity. 

The calculation shows that the stoichiometric yield RY is acceptable, but the theoretical balance yield BAt poor, because catalyst complex lost after reaction. A significant improvement would be the use of solid catalyst. Other alternative is regeneration of A1C13 complex by recycling. The two solutions would lead to the same theoretical yield, but with different costs. Therefore, a deeper investigation should take into account a cost flow analysis too. More details can be found in Christ [2]. 

The solubility limit of NaBEL in water is about 35 wt% at 25°C. Assuming 100% stoichiometric yield in Reaction [1], one liter of 35 wt% NaBEL, 5 wt% NaOH aqueous solution (measured density = 1.05 g/mL) yields ... 

Thus the maximum (stoichiometric) yield of hydrogen is 2+m/2n-k/n moles per mole of carbon in feed. Therefore, 32.4 g of hydrogen could be theoretically obtained from 1 liter of the carbohydrate-derived fraction of the bio-oil. 

Cumene manufacture consumed about 10 percent (2.2 billion lb) of the propylene used for chemicals in the United States in 1998. It is prepared in near stoichiometric yield from propylene and benzene with acidic catalysts (scheme below). Many catalysts have been used commercially, but most cumene is made using a solid phosphoric acid catalyst. Recently, there has been a major industry shift to zeolite-based catalyst. The new process has better catalyst productivity and also eliminates the environmental waste from spent phosphoric acid catalyst. It significantly improves the product yield and lowers the production cost. Cumene is used almost exclusively as feed to the cumene oxidation process, which has phenol and acetone as its coproducts. 

Strain improvement, to increase the stoichiometric yield, the product concentration and the STY, was, until the early 1990s, generally achieved via classical techniques, i.e. by putting the species under selective pressure. Because the progress depends on the natural mutation frequency, the latter is routinely augmented by the application of mutagenic chemicals, UV radiation etc. 

Raw materials for the fermentation of ethanol are sugar molasses (Brazil), com steep liquor and corn starch hydrolysate (USA). Industrial ethanol fermentation is highly developed and the stoichiometric yield can be as high as 1.9 mol mol-1 [25, 26]. The... 

The anaerobic fermentation of lactic acid is traditionally performed at up to 50°C over 2-8 d at pH 5.5-6.5 (lactic acid bacteria are highly sensitive to acid). The pH is maintained by titration with a base, usually calcium carbonate. The product concentration is kept below approx. 100 g L 1 to prevent precipitation of calcium lactate, as the separation of a precipitate from the biomass would be too elaborate. The stoichiometric yields are high, of the order of 1.7-1.9 mol mob1 (85-95% of the theoretical yield) but the space-time yield, which is ap-... 

When the initial shortcomings of these engineered yeasts, such as low stoichiometric yield and productivity, have been ironed out, it may be expected that lactic acid fermentation in an acidic medium, combined with solvent extraction of the product, will evolve into a procedure of unprecedented efficiency. 

As shown in Fig. 8.10, energy and redox equivalents are required to drive the transformation of glucose into 1,3PD. These are provided by converting some of the glucose all the way into C02, which restricts the stoichiometric yield on glucose to 1.4 mol mol-1 maximum. A stoichiometric yield of 1.18 mol mol-1 of 1,3PD (50% by weight) has been obtained in practice [64], which corresponds with 85% of the theoretical yield, at a product concentration of 135 g L 1. 

E4P and PEP has been studied in much detail the extensive mutagenesis that has been applied to increase the bioavailability of these latter compounds has been reviewed [70-72]. It should be noted that the PTS, which mediates the uptake and phosphorylation of glucose, limits the yield of DAHP from glucose at 0.43 mol mol-1 in a situation that is similar to that described above in Section 8.2.4. If all PEP could be channeled into the aromatic pathway the stoichiometric yield of DAHP could be as high as 0.86 mol mol-1, at least in theory [73]. Various approaches to PEP conservation have been demonstrated [72, 74, 75]. 

L-Phe can be prepared via the enantioselective hydrolysis of N-acetyl-D,L-Phe and microbial reductive amination of phenylpyruvate (see Fig. 8.14) [87]. The stoichiometric yields of these processes were high but the precursors required 3-4 synthetic steps from the basic starting materials in most cases. The phenyl-ammonia lyase route, in contrast [89], provided L-Phe in only two steps from the basic chemicals benzaldehyde and acetic anhydride [90]. The enzymatic step... 

Mobil/Badger Cumene Benzene, propylene (dilute/polymer-grade) Environmentally clean. Achieves stoichiometric yield with high purity 12 2001... 

Energy Requirements. An electrochemical unit (ECU) in the chlorine industry represents the stoichiometric yield of 1 mole of Cl2 and 2 of... 

Synthesis of ureas. Ureas can be synthesized by the reaction of aliphatic amines, carbon monoxide, and oxygen with selenium as a catalyst. For example, n-butylamine (0.1 mole) is dissolved in THF (100 ml.) amorphous selenium (0.005 g.-atom) is added and carbon monoxide is blown through the solution. Then oxygen (or air) is blown through. 1,3-Di-n-butylurea is obtained in stoichiometric yield. The reaction proceeds in two steps as formulated. 

The stoichiometric yield coefficient that relates the amount of product formed per mass of substrate consumed is... 

The product ethylene is formed in a stoichiometric yield with the nitrile and isonitrile, and for methylallenimine, (C2H4) = 0.25 and deactivating mechanism is also operative. The overall mode of decomposition bears a close resemblance to that of the hydrocarbon analog, the methylenecyclopropane ring system. 

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