Optimum reaction temperature

The sulfation reaction does not have an optimum reaction temperature under pressurized operating conditions and the higher partial pressure of oxygen results in increased conversion of sulfur dioxide to sulfur trioxide. 

Exxon Thermal DeNOx Similar to SCR, the Exxon Thermal DeNOx process utilizes the NO /ammonia reaction. However, this process does not use a catalyst to aid the reaction. Rather, tightly controlled temperatures are used to steer the reactions. Optimum reaction temperatures are found between IbOOT (871°C) and... 

The spent acid strength is maintained at about 90 wt% H2SO4. The molar isobutane/alkene feed ratio ranges from 7 1 to 10 1. Typical operating alkene space velocities (LHSV) range from 0.2 to 0.6 h-1 (corresponding to WHSVs from 0.06 to 0.19 h 1). The optimum reaction temperatures range from 279 to 283 K, but some units are operated at temperatures up to 291 K. 

For monosulfonation of PPh3 the reaction mixture can be heated for a limited time [1-3] while multiple sulfonation is achieved hy letting the solution stand at room temperature for a few days [4-10], In this simplest way of the preparation several problems may arise. Under the harsh conditions of sulfonation there is always some oxidation of the phosphine into phosphine oxide and phosphine sulfides are formed, too. Furthermore, selective preparation of TPPMS (1) or TPPDS (2) requires optimum reaction temperature and time and is best achieved by constantly monitoring the reaction by NMR [10] or HPLC [7]. Even then, the product can be contaminated with unreacted starting material. However, 1 can be freed of both the non-sulfonated and the multiply sulfonated contaminants by simple methods, and in the preparation of TPPTS (3) contamination with PPh3, 1 or 2 is usually not the case. Direct sulfonation with fuming sulfuric add was also used for the preparation of the chelating diphosphines 34-38, 51, 52. 

An even more powerful option is the use of micro flow reactors, which can potentially be automated to provide a complete series of optimisations [49]. For example, a glycosylation reaction was monitored over a series of reaction temperamres. Although the optimum reaction temperature for maximum yield was determined to be — 60°C, it was noted that by increasing the temperature of the reaction to — 35°C the yield only dropped shghtly but the reaction rate increased considerably. It was therefore possible to achieve a ten-fold increase in production rate. The complete optimisation took one afternoon and consumed 2 mg of starting material. 

The temperature optimization for the RAFT polymerization of EAA revealed an optimum reaction temperature of 70 °C. Block copolymers with a poly(methyl acrylate) (PMA), a poly(n-butyl acrylate) (PnBA), a PMMA, or a poly(A,A-dimethyl aminoethyl methacrylate) (PDMAEMA) first block and a poly(l-ethoxyethyl acrylate) (PEEA) second block were successfully synthesized in an automated synthesizer. The synthesis robot was employed for the preparation of 16 block copolymers consisting of 25 units of the first block composed of PMA (exp. 1 ), PnBA (exp. 5-8), PMMA (exp. 9-13), and PDMAEMA (exp. 13-16) and a second block of PEEA consisting of 25, 50, 75, or 100 units, respectively. The first blocks were polymerized for 3 h and a sample from each reaction was withdrawn for SEC analysis. Subsequently, EAA was added and the reactions were continued for 12 h. The molar masses and PDI values of the obtained block copolymers are shown in Fig. 15. 

Activity measurements. Activity and selectivity measurements were performed at 10 psig in a 14-mm internal diameter glass fluid bed reactor using 25 grams of 90 to 38 micron catalyst particles. A reactant mixture of approximately 18 volume % 02 7 volume X NH3 and 7 volume % CH3OH and the balance of helium was fed to the catalyst, and temperature and contact time were varied to find the optimum yield of HCN. Optimum reaction temperatures were found to range from 425° to 475°C with contact times of 3 to 5 seconds (calculated at STP>. Fixed bed reactor studies produced similar results. The yields reported in this paper are based on carbon fed, unless otherwise noted. More details on catalyst performance can be found in our patents (7,8). 

The rate of addition should be as rapid as possible provided that the proper temperature is maintained. Deviation of more than 5° from the optimum reaction temperature of 95° results in reduced yields. 

The optimum reaction temperature is approximately 30°. A yellow product results at higher reaction temperatures, while lower reaction temperatures lead to an uncontrollable reaction resulting from the base-initiated polymerization of acrylonitrile. 

The initiation of crystallization indicates the optimum reaction temperature for the catalyzed cyanosilylation of p-benzo-quinone. The use of higher temperatures results in excessive darkening of the product and a decrease in yield. 

The optimum reaction temperature of 280 °C is the same as the temperature for the direct reaction of methylene chloride, indicating that... 

The decarbonylation of furfural to give furan is best carried out at rather high temperatures. The following catalysts have been described Pd or Pd on charcoal,30 calcium oxide,31 32 zinc and iron chromite,33 or zinc, chromium, and manganese oxide (from ammonium chromate and manganese nitrate).34 The optimum reaction temperature with... 

The 3,3-dialkyl-l-aryltriazene (0.1 mmol) was treated with TBAF or CsF (0,2 mmol) in the presence of MsOH or TFA (5 mol equiv), or cation-exchange resin (BioRaD AG 50W-X12-hydrogen form), in anhyd MeCN, trichloroacelonitrilc. THF, DMF, DIVlSO. PhBr, toluene, CCI4 or 1,2-dichlorobenzene (3 ml,). The optimum reaction temperature for aromatic triazene decomposition in most solvents was 70-80 C. 

Commercial SCR catalyst used in connection with coal-based power stations are generally composed of base metals, since platinum-group metal catalysts are too readily poisoned and have too narrow an operating temperature window for this application. Favored compositions are titania-based together with active components, normally oxides of vanadium, tungsten, or molybdenum. For these systems the optimum reaction temperature is usually in the range 3(XM00°C. 

Deviation of the reactor temperature from the optimum reaction temperature is directly detected by the on-line Raman FT-spectrometer as shown in Fig. 5. 

Table 1. Optimum reaction temperature and activation energy of the reaction of methylchlorosilanes with isolated silanol groups of the silica surface.

A spectacular example of stability enhancement through immobilization has been reported for the enzyme catechol-2,3-dioxygenase.27 This enzyme, isolated from the thermophilic bacterium Bacillus stearothermophilus, catalyzes the conversion of catechol to 2-hydroxymuconic semialdehyde (which can be monitored by absorbance at 375 nm). The soluble enzyme exhibits maximal activity at 50 °C, but following immobilization on glyoxyl agarose beads with a borohydride reduction step, the optimum reaction temperature shifted to 70 °C. At a total protein concentration of 0.010 mg/mL and a temperature of 55 °C, the half-life of the soluble enzyme was 0.08 h, while the enzyme-modified beads had a half-life of 68 h. This represents a 750-fold enhancement of stability that has been attributed to the prevention of subunit dissociation upon immobilization. 

Temperature. The catalyst activity is quite sensitive to temperature changes. As temperature increases, the catalyst activity and the ethylene conversion increase. However, the selectivity to butene-1 production is adversary affected through the increase in by-product, mainly hexenes formation. Another undesirable effect of temperature increase is the extent of polymer formation. The optimum reaction temperature range is generally between 50 to 60°C [141. 

Glyoxylic acid was found to be produced by a vapor-phase oxidative dehydrogenation of glycolic acid over iron phosphate catalysts with a P/Fe atomic ratio of 1.2. The best results were obtained with iron phosphates freshly calcined at 400 to 450°C. Reduced iron phosphates showed a markedly lower activity. The optimum reaction temperature was about 240°C. The selectivity to glyoxylic acid was 74 mol% up to the glycolic acid conversion of about 70% the highest yield of glyoxylic acid was 56.5 mol% at the conversion of 80 %. 

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