On product yield

Utilisa tion of shale oil products for petrochemical production has been studied (47—51). The effects of prerefining on product yields for steam pyrolysis of shale oil feed and the suitabiUty of Green River shale oil as a petrochemical feedstock were investigated. Pyrolysis was carried out on the whole oil, vacuum distillate, and mildly, moderately, and severely hydrogenated vacuum distillates. 

Effect of RDS pretreatment on product yields from RFCC (with and without RDS) ... 

The product distributions shown in Figures 9.7 and 9.8 are obviously quite different, so we again see that the manner of contacting can have significant effects on product yields. We... 

The effect of the H-Beta ratio (y in wt%) in the dual-bed Pt/Z12(x) HB(y) catalyst system on the benzene purity at a reaction temperature (Tr) of 623 K is shown in Fig. 1. It is evident that the benzene purity gradually increased with increasing H-Beta ratio (Fig. la), eventually reaching a plateau value which meets the industrial specification of 99.85% at y 40 wt%. The effects of catalyst bed ratio on product yields are shown in Fig. lb. Comparing to the single-bed catalyst Pt/Z 12 (i.e., y = 0), the overall premium product yields of benzene and xylene (A68 yield) over the dual-bed catalyst Pt/Z12(x) HB(y) system reached an maximum at y 10 wt%. That the A68 yield dwindled and tetramethylbenzene (TEMB) increased with further increase in the H-Beta ratio may be attributed to the larger pore opening possessed by the bottom (H-beta) catalyst, which may provoke disproportionation of TMB to form tetramethylbenzene (TEMB) [8],... 

Tables 4.4 and 4.5 show the effect of temperature on product yield and composition from the pyrolysis of mixed municipal solid waste (MSW) and bituminous coal. Other data11 show that beyond a certain temperature char yield does...

Table 4.4 Sampling of Data Extracted From the Study By Klass (1998) Showing the Effects of Temperature on Product Yield and Gas Compositions From Pyrolysis of Combustible Fraction of MSW...

In CRE textbooks (Hill 1977 Levenspiel 1998 Fogler 1999), the types of reactors considered in this book are referred to as non-ideal. The flow models must take into account fluid-mixing effects on product yields. 

Grain legumes have also been processed into refined starch (10,11) and protein isolates (12,13,14) by procedures derived from the traditional corn starch and soybean protein industries (15). However, comparative data on product yields, composition and losses have not been published. A commercial plant for the wet processing of field pea into refined starch, protein isolate and refined fiber has been established in Western Canada. Little is known about the characteristics of the protein isolate or refined fiber product. Water-washed starch prepared from the air-classified starch fractions of field pea (16,17) and fababean (6) have been investigated for certain physico-chemical and pasting properties. Reichert (18) isolated the cell wall material from soaked field pea cotyledons and determined its fiber composition and water absorption capacity. In addition, the effects of drying techniques on the characteristics of pea protein Isolates have been determined (14). 

The reaction of dicyclohexylborane and trifluoromethanesulfonic acid is highly exothermic. On one occasion, the checkers cooled the reaction in an ice bath during the addition period, with no effect on product yield. The submitter reports that he once experienced a sudden vigorous reaction under cooling conditions, probably due to accumulation of unreacted triflic acid. It thus appears safer to add the acid at room temperature, slowly, so that it reacts immediately. 

A feasibility study on the application of H-NMR petroleum product characterization to predict physicochemical properties of feeds and catalyst-feed interactions has been performed. The technique satisfactorily estimates many feed properties as well as catalyst-feed interactions to forecast products yield. There are, however, limitations that have to be understood when using the H-NMR method. The technique, in general, is not capable either to estimate the level of certain contaminants such as nitrogen, sulfur, nickel, and vanadium when evaluating feed properties or the effect of these contaminants on products yields while testing catalyst-feed interactions. 

Table I shows the effects of Mel/DME and CO/DME ratios in the feed gas on product yields. With increasing Mel/DME ratio both methyl acetate yield and selectivity increased. The yield of methyl acetate increased with an increase in the CO/DME ratio whereas its selectivity decreased. In the case of methanol carbonylation on Ni/A.C. catalyst, the product yield and selectivity were strongly affected by CO/MeOH ratio but not by Mel/MeOH ratio (14-16). The promoting effect of methyl iodide on the methanol carbonylation reached a maximum at a very low partial pressure, that is 0.1 atm or lower. However, both CO/DME and Mel/DME ratios were important for regulating the product yield and selectivity of the dimethyl ether carbonylation. This suggests that the two steps, namely, the dissociative adsorption of methyl iodide on nickel (Equation 4) and the insertion of CO (Equation 5) are slow in the case of dimethyl ether reaction.

The next few subsections will present data for the products in the radiolysis of water with a wide variety of heavy ions. Product yields with heavy ions are rarely constant in time, but most of them vary slowly in the microsecond region. Furthermore, most chemical systems used to probe yields with heavy ions were developed for examining fast electron or y-radiolysis in the microsecond region. The following discussion on product yields can be assumed to apply to the microsecond time regime. Because a wide range of systems are used to determine product yields, consistency between the different experiments can be obtained by examination of the material balance. The net decomposition of water can be obtained by setting the number of H atoms in each product equal to the number of H atoms in the net water decomposed to form that product and similarly for O atoms [16]. 

In a recent review, Tao etal. [34] describe the partial fluorination and the perfluorination of organics with particular emphasis on medically important compounds and pharmaceuticals. The selective electrofluorination (SEF) of olefins and active methylene groups is reviewed by Noel et al. [35] In the case of heterocycles, nuclear fluorination is known to be the predominant process. However, in aromatic compounds, nuclear substitution as well as addition proceeds simultaneously, leading to the formation of a mixture of products. The influence of solvents, supporting electrolytes, and adsorption on product yield and selectivity is summarized and evaluated. Dimethoxyethane is found to be a superior solvent for SEF processes. Redox mediators have been employed to minimize anode passivation and to achieve better current efficiencies. 

Figure 6. Effect of temperature on product yields in 3% NaOH (1 h reaction time).

The first of these problems appears to have a reasonable expectation of solution. There are a few publications which state that supported metals can be used to promote some of the organometallic reactions commonly run with soluble catalysts (refs. 2-4). In these reports, though, the use of the supported metal is generally included only as an entry in a table describing the effect of changing reaction parameters on product yield and/or selectivity. The fact that a heterogeneous catalyst was used is seldom discussed. When it is mentioned, it is... 

Mechanistic arguments based on product yields have been used to attempt to decide whether a free carbocation is the reaction intermediate in Sn 1 reactions. If a free carbocation is formed... 

Asymmetric imidations of aryl alkyl sulfides with [(tosylimino)iodo]ben-zene, catalyzed by various chiral (salen)manganese(III) complexes, have been investigated in some detail [31,32]. The influence of catalyst structure, solvent, temperature, 3°-amine AT-oxides, and the presence of molecular sieves on product yields and the enantioselectivity of imidation with 17 was evaluated. Enan-tioselectivities as high as 90 % ee and 97 % ee with methyl 2-nitrophenyl sulfide and methyl 2,4-dinitrophenyl sulfide, respectively, were achieved. 

The results clearly show that temperature and time at 95% and 99% confidence level respectively have a significant effect on production yield. It is also clear that there is no interaction between temperature and time factors. Experimental error is small with respect to interaction so that the used measurement equipment can be considered satisfactory. 

After realizing each trial, it is possible to determine factor effects on product yields ... 

In all these processes, there are commmon needs to form crystals, to cause them to grow, and to separate the crystals from the residual liquid. While conceptually simple, the operation of a process that utilizes crystallization can be very complex. The reasons for such complexity involve the interaction of the common needs and process requirements on product yield, purity, and, uniquely, crystal morphology and size distribution. In the following discussion, the interactions will be discussed and general principles affecting crystallizer operation will be outlined. More... 

Gravimetric Results of Catalytic Cracking. Experiments were conducted to assess the effects of temperature, cat-to-oil ratio, and feedstock composition. In addition to the effect of variables on product yields, it was also important to identify the relative influence of thermal reactions, since free-radical reactions may adversely affect product quality. A series of experiments was conducted in the temperature range of 412°-415°C because this is the temperature of maximum increase in production from thermal cracking and catalytic vs. thermal effects are more easily discernible at this temperature. 

---