Temperature selectivity affected

Temperature also affects production rates but, through its influence on the thermal expansion of water, it also induces changes in the depth of vertical mixing and resistance to wind-stirring processes. Reactions to temperature of other components of the food chain are also important in the regulation of phytoplankton biomass by consumers. Different phytoplankton species, with important morphological differences, are differentiated selectively by the interplay of these factors. " ... 

The selection of optimum reactor inlet and outlet temperatures is affected by catalyst activity, and catalyst stability, and the need to minimize operating and investment costs. When the special BASF methanation catalyst is used, inlet temperatures of 260°-300°C or even lower are quite acceptable (see Table II). The final decision on design inlet temperature is affected by engineering requirements. 

Increasing the temperature may affect the selectivity adversely, but if it is acceptable for yield and selectivity reasons, it is preferred to a decrease in feed rate, which decreases the reactor productivity. 

Another simple oligomerization is the dimerization of propylene. Because of the formation of a relatively less stable branched alkylaluminum intermediate, displacement reaction is more efficient than in the case of ethylene, resulting in almost exclusive formation of dimers. All possible C6 alkene isomers are formed with 2-methyl-1-pentene as the main product and only minor amounts of hexenes. Dimerization at lower temperature can be achieved with a number of transition-metal complexes, although selectivity to 2-methyl-1-pentene is lower. Nickel complexes, for example, when applied with aluminum alkyls and a Lewis acid (usually EtAlCl2), form catalysts that are active at slightly above room temperature. Selectivity can be affected by catalyst composition addition of phosphine ligands brings about an increase in the yield of 2,3-dimethylbutenes (mainly 2,3-dimethyl-1-butene). 

Examination of the way Equations 12—17 and 12-18 are affected by incorrect trial values of rig or nL will provide guidance for rapid convergence to the correct values. Figure 12-1 shows the results of calculations with Equation 12-17. The correct value of fig is the value which makes the summation equal 1.0. Regardless of the pressure or temperature selected, a trivial solution is obtained at fig equals zero. 

The composition of volatiles released from a food is different when it is sniffed (via orthonasal route) and when it is eaten (via retronasal route). This is partially due to conditions in the mouth that selectively affect volatility, thus altering the ratio of compounds that volatilize from a food system. Mouth temperature, salivation, mastication, and breath flow have all been shown to affect volatilization (de Roos and Wolswinkel, 1994 Roberts et al., 1994 Roberts and Acree, 1995 van Ruth et al., 1995c). The ideal gas law describes the effects of temperature. Saliva dilutes the sample, affects the pH, and may cause compositional changes through the action of the enzymes present (Burdach and Doty, 1987 Overbosch et al., 1991 Harrison, 1998). Mastication of solid foods affects volatility primarily by accelerating mass transfer out of the solid matrix. The gas flow sweeps over the food, creating a dynamic system. The rate of the gas flow determines the ratio of volatiles primarily based on individual volatilization rates and mass transfer. 

External fields are applied widely in separation systems. The most common fields used are based on electrical and sedimentation (both centrifugal and gravitational) forces. Gradients in solvent composition and temperature maintained by actions external to the system may also be considered as external fields defined in their broadest context (see Chapter 8). All of these fields are capable of changing the equilibrium distribution of chemical components. Furthermore, they may be selective, affecting one component differently from another, a basic requirement for separation. 

Free Radical Cure UV Adhesives. As with any adhesive, formulation variables are critical to the processing and performance characteristics. Variables such as oligomer selection, modifiers and additives, monomer structure, molecular weight, and glass transition temperature directly affect application and performance properties. 

Most of these properties can be examined in the effective conditions in wfaidi the solvent is used, particularly temperature, which affects the solvent power, selectivity, the immiscibility zone etc. (see diagram a of Fig. 4.4). 

Several silyl ethers can be cleaved selectively under a wide range of conditions. It is possible to cleave, for example, a TBS-ether in the presence of other TBS-ethers, if they vary in their reactivity. The primary TBS-ether in 17 is cleaved under mild acidic conditions with camphorsulfonic acid in dichloromethane/methanol at room temperature without affecting the three secondary TBS-ethers. ... 

As mentioned, temperature seriously affects the migration time, whereas its effect on selectivity is not remarkable. It is important to maintain temperature precisely to obtain reproducible results. 

In the present study Ru-Sn/Al203 catalysts were calcined in air and reduced under H2 flow at various temperatures. The effect of calcination temperature on the performance of catalysts is shown in Table 4. Calcination was performed for 4 h at the specified temperatures. After calcination the catalysts were subsequently reduced tmder the flow of H2 at 350 °C for 4 h. Results listed in Table 4 indicated that the calcination temperature hardly affected the conversion of EL, while it showed clear influence on the product selectivity. Upon increasing the calcination temperature the selectivity of ROH passed through a maximum at 350 °C. Appreciable selectivity of hydrocarbons along with conparatively lower selectivity of ROH over the catalysts, calcined at 250 °C or at a lower temperature, can be explained by a large amount of residual chlorine. On the other hand, calcination of the catalyst at 400 °C or at a higher temperature may result in the segregation of surface Ru and Sn species, and hence lower selectivity of ROL [4],... 

Carboxyl protection. Tetralyl esters can be selectively cleaved by Me SiCl-Nal in MeCN at room temperature without affecting benzhydryl esters and p-methoxybenzyl esters. 

The effect of calcination temperature on the performance of CZA-4 catalyst is also shown in Table 30. The calcination of CZA-4 catalyst was performed in air at 350 °C. After calcination the catalyst was subsequently reduced under the flow of H2 at different temperatures. Results listed in Table 30 indicated that the reduction temperature hardly affected the product selectivity and the yield of dodecanol. 

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