Reaction parameters pressure

The development of a viable process for the HPB ester took more than a year. Even before the age of high-throughput screening, the obvious strategy was first, to screen for the best catalyst, modifier and solvent, second, to optimize relevant reaction parameters (pressure, temperature, concentrations, etc.) and, finally, to scale-up and solve relevant technical questions. Indeed, during the course of the process development more than 200 hydrogenation reactions were carried out The most important results of this development work may be summarized as follows ... 

Whereas various studies have been published dealing with new water-soluble ligands and their effects on the hydroformylation of higher alkenes, only little data are available in the academic literature on the Rh-TPPTS catalyst system, especially without any additives. This section will provide some information on the effect of various reaction parameters (pressure, P/Rh ratio, rhodium concentration, alkene chain length, etc.) in the two-phase hydroformylation of higher alkenes... 

The Catatest plant allows the reaction parameters pressure, temperature, and liquid and gas feed to be varied over wide ranges Figure 13-18 shows just a few results. The reaction products in both test series were benzyl alcohol and toluene. Considerable influence of the solvent and the temperature on the product distribution and the conversion were found. 

A useful device to have installed in a stirred autoclave is a liquid sampling tube by which liquid samples are withdrawn under pressure through a filter attached to the lower end of the tube. This device is especially useful for analysis of reaction progress and supplements information obtained from pressure-drop determinations. It is much easier to improve a less than satisfactory yield, if it can be determined what is going wrong and when. For academically orientated persons, a study of the rise and decline of various reaction products, as a function of reaction parameters and catalyst, can be a fertile source of useful publications. 

Instrument failure, pressure, flow, temperature, level or a reaction parameter, e.g. concentration. 

The tuning of solubility with a relatively small jump or fall in pressure can possibly bestow many benefits with respect to rates, yields, and selectivity. Reaction parameters can be changed over a wide range. Replacement of solvents with high boiling points by supercritical (SC) fluids offers distinct advantages with respect to removal of the solvent. SC fluids like CO2 are cheap and environmentally friendly the critical temperature of CO2 is 31 C and the critical pressure 73.8 atm (Poliakoff and Howdle, 1995). Eckert and Chandler (1998) have given many examples of the use of SC fluids. Alkylation of phenol with tcrt-butanol in near critical water at 275 °C allows 2- erf-butyl phenol to be formed (a major product when the reaction is kinetically controlled 4-rert-butyl phenol is the major product, when the reaction is... 

Polyalphaolefin Hydraulic Fluids. Polyalphaolefms are made by oligomerizing alphaolefins such as 1-decene in the presence of a catalyst (Newton 1989 Shubkin 1993 Wills 1980). The crude reaction mixture is quenched with water, hydrogenated, and distilled. The number of monomer units present in the product polyalphaolefin oil depends on a number of reaction parameters including the type of catalyst, reaction temperature, reaction time, and pressure (Shubkin 1993). The exact combination of reaction parameters used by a manufacturer is tailored to fit the end-use of the resulting polyalphaolefin oil. A typical polyalphaolefin oil prepared from 1-decene and BF3- -C4H9OH catalyst at 30 °C contains predominantly trimer (C30 hydrocarbons) with much smaller amounts of dimer, tetramer, pentamer, and hexamer. While 1-decene is the most common starting material, other alphaolefins can be used, depending on the needs of the product oil. 

The Anton Paar Synthos 3000 (Fig. 3.16 and Table 3.5) is the most recent multi-mode instrument to come onto the market. It is a microwave reactor dedicated for scaled-up synthesis in quantities of up to approximately 250 g per run and designed for chemistry under high-pressure and high-temperature conditions. The instrument enables direct scaling-up of already elaborated and optimized reaction protocols from single-mode cavities without changing the reaction parameters. 

The issue of parallel versus sequential synthesis using multimode or monomode cavities, respectively, deserves special comment. While the parallel set-up allows for a considerably higher throughput achievable in the relatively short timeframe of a microwave-enhanced chemical reaction, the individual control over each reaction vessel in terms of reaction temperature/pressure is limited. In the parallel mode, all reaction vessels are exposed to the same irradiation conditions. In order to ensure similar temperatures in each vessel, the same volume of the identical solvent should be used in each reaction vessel because of the dielectric properties involved [86]. As an alternative to parallel processing, the automated sequential synthesis of libraries can be a viable strategy if small focused libraries (20-200 compounds) need to be prepared. Irradiating each individual reaction vessel separately gives better control over the reaction parameters and allows for the rapid optimization of reaction conditions. For the preparation of relatively small libraries, where delicate chemistries are to be performed, the sequential format may be preferable. This is discussed in more detail in Chapter 5. 

The temperature/pressure monitoring mechanisms of modem microwave reactors allow for an excellent control of reaction parameters, which generally leads to more reproducible reaction conditions. 

For cobalt as catalyst, variations in reaction parameters have been studied as a means of controlling the product composition (or isomer ratio). Thus, variations in isomer ratio from 1 1 to about 4 1 were observed under widely differing conditions of temperature, catalyst concentration, partial pressure of hydrogen, and partial pressure of carbon monoxide. 

In an early investigation (28, 59, 60), critical combinations of several reaction parameters were discovered to produce unusually high yields of the linear isomer. The parameters included low partial pressure of carbon monoxide, high concentration of phosphite or aryl phosphine ligands, and low total gas pressure. The catalyst was a soluble complex of rhodium, formed in situ from rhodium metal in many cases. Isomer ratios of 10 1 to 30 1 were obtained by appropriate selection of these reaction parameters. Losses to alkane were minimal, even with Pm as low as 10 psi. Tables XI-XIV illustrate the effects of these various reaction parameters on the product composition. 

The calculated reaction parameters with BP86//B3LYP methods at two higher temperatures (150 and 250 °C) are shown in Tables VI and VII, respectively. Further corrections for low H2 and olefin pressure/concen-tration and high alkane pressure/concentration (36,37) on BP86// B3LYP values are shown in Tables VIII and IX. 

A higher olefin yield may be obtained by variation of the catalyst (small-pore catalyst) or by variation of the process parameters such as reaction temperature, pressure, and feed flow. 

In catalytic processes, such as CO conversion (CO + H20 —> C02 + H2), selective methanisation (CO + 3 H2 —> CH4 + H20) or selective CO oxidation (CO + Vi 02 —> C02), the achievable efficiencies depend on reaction parameters, such as temperature, pressure, volume flow, raw gas concentration and catalyst material. These are capable of achieving contamination levels from 1 % down to a few ppm. The selection of different reaction paths is based on the use of different types of catalyst. 

All reaction parameters including volume rates of the hydrogen, organic and aqueous phase as well as the partial pressure of hydrogen and the reaction temperature are recorded on a PC and can be controlled by process control software, which was developed in the working group. 

Synthetic FT diesel fuels can have excellent autoignition characteristics. The FT diesel is composed of only straight-chain hydrocarbons and has no aromatics or sulfur. Reaction parameters are temperature, pressure and H/CO ratio. FT product composition is strongly influenced by catalyst composition the yield of paraffins is higher with cobalt catalytic ran and the yield of olefins and oxygenates is higher with ironcatalytic ran. 

As mentioned earlier, in the Ruhrchemie-Rhone Poulenc process for propene hydroformylation the pH of the aqueous phase is kept between 5 and 6. This seems to be an optimum in order to avoid acid- and base-catalyzed side reactions of aldehydes and degradation of TPPTS. Nevertheless, it has been observed in this [93] and in many other cases [38,94-96,104,128,131] that the [RhH(CO)(P)3] (P = water-soluble phosphine) catalysts work more actively at higher pH. This is unusual for a reaction in which (seemingly) no charged species are involved. For example, in 1-octene hydroformylation with [ RhCl(COD) 2] + TPPTS catalyst in a biphasic medium the rates increased by two- to five-fold when the pH was changed from 7 to 10 [93,96]. In the same detailed kinetic studies [93,96] it was also established that the rate of 1-octene hydroformylation was a significantly different function of reaction parameters such as catalyst concentration, CO and hydrogen pressure at pH 7 than at pH 10. 

Reaction High-Pressure Rate Parameters" A, I/s E, kcal/mol ... 

A successful two-stage liquefaction process will need to maintain a relatively consistent H-donor cs ability in its recycle solvent arnl should react positively to rectify variations in the consistency outside acceptable limits. In order to react to these variations, the process will need the ability to adjust reaction parameters (e.g. pressure, temperature, throughput, catalyst activity), probably according to its H-donor ability. Hence there is a need to monitor the H-donor content of the solvent. 

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