Reactors improved sampling

Formaldehyde Indoor, ambient air GD UV—Vis 0.08 ppbv Flow injection system two parallel scrubbers for improving sampling rate heated (50° C) main reactor [537]... 

The first set of results from the TAP reactor, as shown in Figure 3, shows the 1,2 C vinyl acetate (MW=88) response curve for the four catalyst samples. The transient response suggests that KOAc dramatically accelerated the desorption of the vinyl acetate off the surface of the catalyst (peak maximum at 7.5 seconds without KOAc, 5.5 seconds with KOAc on average). In addition, Au enhanced the desorption rate of the vinyl acetate, but to a much lesser extent. It is also seen that Au improved the production rate of the catalyst (peak areas Pd-Au > Pd and Pd-Au w/KOAc > Pd w/KOAc). 

The above-mentioned targets refer to general advantages of micro reactors [42, 80, 100, 114, 119]. Enhanced transfer and better controlled residence time improve conversion and selectivity. The tools have small internal volumes, allowing one to generate flexibly a multitude of samples in serial or parallel fashion. Synthesis can be combined with a multi-step procedure. The economy of micro-reactor processes has not really been analyzed so far however, it is clear that as laboratory tools they allow in a number of cases technical expenditure, personnel and costs to be reduced. 

By incorporating the entire analytical scheme (enzyme reaction and electrochemical detection) into the flow system a great improvement in precision can be realized. Sample manipulation is minimized because only a single injection into the flow system is required versus sampling of aliquots for the off-line method. Precision is also improved because the timing of the enzyme reaction and detection are much better controlled in the flow system. Finally, less of both enzyme and sample are needed with on-line enzyme reactor methods. 

Processing the carbon separately with internal baffles in SCWO reactor to ensure sufficient residence time alternatively, decontaminating carbon to 5X using one of several processes (e.g., heated discharge conveyor or A1 filter cake dryer) Implementation of improved filtration technique and verification of correct SCWO feed composition by sampling and analysis... 

The samples obtained by this procedure, containing various ratios of zeolite and mesoporous materials, were tested in 100% steam for 5 hours at temperatures of 650 and 815°C, respectively, in a fixed bed reactor. Prior to the tests the samples were calcined at 550°C in N2 (1 hour) and dry air (4 hours). Synthesis and characterization data for the most interesting samples with regard to improved hydrothermal stability are listed in Tables 1 and 2. 

By coupling an ultrasonic probe with a microwave reactor and propagating the ultrasound waves into the reactor via decalin introduced into their double jacket design, Chemat et al. studied the esterification of acetic acid with propanol and the pyrolysis of urea to afford a mixture of cyanuric acid, ameline and amelide (Scheme 9.19)136. Improved results were claimed compared to those obtained under conventional and microwave heating. The MW-US technique was also used to study the esterification of stearic acid with butanol and for sample preparation in chemical analysis137,138. 

Finally, Rong and coworkers discuss the roll of surface oxygen on the MCS process75. Rong employed a lab-scale stirred bed reactor and then applied XPS to analyze the silicon samples before and after the reaction. The reactivity of silicon depended on the initial thickness of the native oxide on the silicon. After the reaction the surfaces of all of the samples were mostly covered with Si02. There was no observed correlation between the surface and bulk O content. XPS analysis showed the presence of Al, Ca and Ti impurities in some samples. Titanium on the surface appeared to increase the reactivity, whereas Ca decreased the selectivity of Di formation. Addition of ZnO to the silicon before CuCl improved reactivity and also decreased the induction period of the reaction. XPS studies of samples prepared in this manner exhibited a lower Zn surface concentration compared to the samples where CuCl, Si and ZnO were mixed together. 

Schuth s group developed in the past a number of reactors similar to conventional testing methods with different degrees of sample integration. For multiphase reactions a 25-fold stirrer vessel reactor was developed [70] and for heterogeneous gas-phase reactions a 16-fold fixed-bed reactor was presented [71], which was later followed by a 49-fold parallel reactor [135], The reactor in Figure 3.42 was used for methanol production from Syngas at up to 50 bar and was essentially an improved version of the 49-fold reactor described in [135],... 

Figure 2a illustrates the improvement in attrition resistance of a VPO catalyst by the addition of only 10% silica as PSA. Both samples of VPO, one with no PSA added and the other with 10% PSA, were tested as catalysts in the butane oxidation process to make maleic anhydride and showed no difference in activity or selectivity. Both fluid bed and recirculating solids reactors were used for the tests of catalytic performance (1) (2). 

Micro activity test (MAT). This test was developed and standardized by ASTM (ASTM-D-3907). In the MAT test, a sample of cracking catalyst is contacted with gas oil in a fixed-bed reactor. Gas chromatographic analysis on gas and liquid products is used to determine the yield structure. Recently, the MAT conditions have been adapted to simulate commercial units more accurately in terms of contact times. A higher catalyst activity results in improved conversion and higher regenerator temperature. 

Table IV summarizes the results of methanol conversion over the catalyst samples employed in the TPD study 30). The reaction was conducted in a conventional fixed-bed flow reactor under the conditions given in the table. The results are in agreement with those of the TPD measurement. Na - and H -TSMs are inactive for the methanol conversion, whereas Ti -TSM promotes dehydration, converting 50% of the fed methanol into dimethyl ether and a small amount of methane. The negligible activity of Li -Hect is improved slightly by exchanging the Li ion with and dramatically by exchanging Li with Ti. Na -Bent is an acidic clay. All of the three Bent catalysts, even Na -Bent, show higher activity than Ti -TSM, and the hydrocarbon yield reflects this difference in catalytic activity. Na -Bent is sufficiently active to give 60% conversion but has no ability subsequently to dehydrate dimethyl ether into hydrocarbons. The activity of H -Bent is higher than that of Na" -Bent, but the hydrocarbon yield is as low as 9%. As expected from the results of TPD measurement, the activity of Ti -Bent is remarkably high and converts 60% of fed methanol into hydrocarbons that are a mixture of methane, C2-5 olefins, and a small amount of Cs hydrocarbons.

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