Oxidation products Pyrex reactor

The thermal oxidation of C2F4 was examined between 280 and 400°C in a static system by Peterson and Colwell.132 In addition to c-C3Fe they measured the total oxidation products (principally CF20) as C02. Their results were not reproducible and differed in Pyrex and nickel reactors. Nevertheless it appeared that product formation occurred with an activation energy in the neighborhood of 20-30 kcal/mole. 

Methanol oxidation was carried out in a conventional flow apparatus at atmospheric pressure. The feed mixtures were prepared by injecting the liquid methanol into air flow with a Gilson 302 pump. The catalyst was diluted with inert carborundum (1 3 volume ratio) to avoid adverse thermal effects, and placed in a tubular pyrex reactor with a coaxially centred thermowell with thermocouple. The reactor outlet was kept at 403 K, to prevent condensation of liquid products and formaldehyde polymerization, and it was connected with multicolumn Shimadzu GC-8A gas chromatograph with thermal conductivity detector. The column system used (1.5m of Poropak N+1.5m of Poropak T+0.9m of Poropak R) could separate CO2, formaldehyde, dimethylether, water, methylformate, dimethoxymethane and formic acid. The last product was never detected. 

On the other hand, studying the influence of the surface material on the DMTM process in one [140] of a series of works, where a very high selectivity of methanol formation (P = 30 atm, T = 350 °C, tj- > 100 s) was observed, revealed no significant differences in the selectivity and yield of methanol in reactors with different surfaces, such as Pyrex, Teflon, stainless steel, silver, and copper. In these experiments, the selectivity of methanol formation on all surfaces reached values close to 90% or more, whereas the methanol yield was as high as 10.7%. However, the authors do not exclude the possibility of influence of the surface material on the temperature and reaction time. In particular, it was found that the maximum selectivity in reactors with metal surfaces was achieved at temperatures higher by nearly 50 °C. This is probably due to the fact that, at lower temperatures in the presence of a metal surface, the oxidation occurs mostly in the heterogeneous mode with the formation of mainly deep-oxidation products. 

By contrast, in a copper reactor, a complete conversion of methanol within 40 s occurred over a temperature range of 300—500 °C. The reaction over a well-oxidized copper surface predominantly produced CO2 and H2O in a ratio of 2 1, whereas the main products formed over the reduced surface were CO and H2. Among the other products, the reaction over the reduced copper surface yielded dimethyl ether, which is usually not detected in the DMTM products. In a Pyrex reactor heated to 300 °C, no decomposition of methanol was observed, only its adsorption. At 350 °C, however, some decomposition occurred, as judged by the appearance of trace amoimts of CO2 and H2O. The decomposition of acetaldehyde took place on surfaces of all the above types. 

The authors of [236] performed a more thorough analysis of the products of this reaction in the same two-section stainless steel flow reactor with a Pyrex liner at a pressure of 34 atm. The main oxidation products detected in the gas and liquid phases were methanol, ethanol, carbon oxides (primarily CO), water, methane, ethylene, propane, n-butane, formaldehyde, acetaldehyde, formic acid and acetic add, dimethoxymethane, dimethyl ether, acetone, and hydrogen. The selectivity of formation of incomplete oxidation products was high, while the selectivity to carbon oxides did not exceed 16—28% at an oxygen concentration of 3.6—12.8%. TTre best results were obtained at 287 °C and an oxygen concentration of 6.6% the ethane conversion was 6.2% whereas the total selectivity of alcohols was 57% at an ethanol-to-methanol ratio of 0.47. The liquid products contained 37% methanol and 17% ethanol. 

PCE was oxidized in a fixed-bed continuous flow reactor. The reactor was a 6-mm-o.d. Pyrex glass tube operated in the down flow mode. A reactant mainly containing air with 30 10,000 ppm of PCE was fed into the reactor charging 60/80 mesh size catalyst at a flow rate of 600 ml/min to avoid mass transfer resistance. The reaction temperatures were maintained at 350 °C under atmospheric pressure as a typical reactor condition [9]. The feed and product streams of the reactor were analyzed by on-line H.P. 5890A gas chromatography (GC) with TCD and FID detectors. The steady-state conversion of PCE was calculated based upon the difference between inlet and outlet concentrations of PCE. It has also been examined that more than 90% of PCE is converted to CO and CO2 by carbon balance. More detailed experimental procedures are described elsewhere [2]. 

Ouyang et al. [147] studied the preferential oxidation of carbon monoxide in silicon reactors of the smallest scale fabricated by photolithography and deep reactive ion etching. The reactors had two gas inlets for reformate and air, a premixer, a single reaction channel, and an outlet zone where the product flow was cooled. The chaimels were sealed by anodic bonding with a Pyrex glass plate. Full conversion of carbon monoxide was achieved between 170 and 300° C reaction temperature. 

Debono et al. used batch reactor for photocatalytic oxidation of decane at ppb levels [33]. This reactor consisted of a Pyrex glass chamber (total volume 120 dm ) was illuminated by nine PL-L-40 Philips UV lamps. The photocatalyst used for experiments (Ti02-P25) was placed in the lower part of the reactor chamber. It was found that formaldehyde, acetaldehyde, and propanal were the main by-products formed in the... 

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