Micro-selectivity test

For light feedstocks and low metals operations, determining the coke selectivity by making use of yields from a Micro Activity Test (MAT) is generally the preferred route. Several modifications of the test and test procedures, for... 

In this work Micro Activity Tests with an aluminosilicate MCM-41 and a silica-containing VPI-5 were carried out using n-hexadecane as the model feed. Special emphasis was given to the catalytic activity, thermal stability and selectivity of the different materials studied in comparison with a commercial equilibrium FCC catalyst. Additionally, the possible structural and textural changes during the above-mentioned catalytic process were characterized. 

In the present work we report the results we have obtained from optimizing a synthesis procedure described by Perez et al. [4] and Martens et al. [6] for selected silicon sources and different Si/Al ratios in the synthesis gels. Results from Micro Activity Tests (MAT) at 524°C with atmospheric residue as the feed, and pulse reactor tests at 480°C with trans-decalin as feed, are discussed. 

The traditional Micro Activity Test (MAT) remains the main tool for basic FCC research and catalyst and feedstock evaluation (O Connor and Hartkamp, 1988 Campagna et al., 1986). This test was developed because of its simplicity, reproducibility and quickness of evaluation in comparison to pilot units. The MAT method is an ASTM procedure (ASTM D-3907-80) which comprises a fixed bed of 4 grams of catalyst, operated with continuous oil vapour feed for 75 seconds at a temperature of 482°C under a cumulative catalyst to oil ratio of 3. This specific form of the MAT procedure has not been successful in predicting commercial unit performance and provides only very limited information on selectivity (Carter and McElhiney, 1989 Mauleon and Courcelle, 1985 O Connor and Hartkamp, 1988). In general, catalyst choice based solely on MAT data is questionable and rarely done and it is not suited for simulating commercial operation. Its main use is in the relative comparison of activity of FCC catalysts (Humphries and Wilcox, 1990). 

Alia- testing, the following test methods were performed on the selected tested specimens Visual examination of the specimens was performed to identify the modes of failure. Oxidation induction time (OIT) was performed in general accordance with ISO 11357-6-2002 (E) [10] at 200 °C. Specimens wo-e taken liom the inner and outer surfaces as well as liom the bulk pipe wall and Micro-attenuated total reflection Fourier Transform Infrared Spectroscopy (micro-ATR) was performed. The inner surface and the fracture surface were examined. Scaiming Eleetron Microscopy (SEM) coupled with Energy Dispersive X-ray analysis (EDX) was performed on the iimer surface and the fiacture surface. 

A growing number of research groups are active in the field. The activity of reforming catalysts has been improved and a number of test reactors for fuel partial oxidation, reforming, water-gas shift, and selective oxidation reactions were described however, hardly any commercial micro-channel reformers have been reported. Obviously, the developments are still inhibited by a multitude of technical problems, before coming to commercialization. Concerning reformer developments with small-scale, but not micro-channel-based reformers, the first companies have been formed in the meantime (see, e.g., ) and reformers of large capacity for non-stationary household applications are on the market. 

In a more comprehensive follow-up work, the selectivity on OAOR-modified silver could be raised to 65%, still without the presence of promoters such as 1,2-dichloroethane [4]. This value is by far better than most values known in the literature for the same catalyst. The best value finally obtained was 69% and approaches the industrial limit of 80% that was obtained with promoters and a different, better catalyst, kglk 20y A similar catalyst type (Aluchrom catalyst) was also tested in the micro reactor, but so far yielding lower results, the best selectivity measured being 58%. 

Propene is an intermediate utilized in the chemical and pharmaceutical industries. The partial oxidation of propene on cuprous oxide (CU2O) yields acrolein as a thermodynamically imstable intermediate, and hence has to be performed under kinetically controlled conditions [37]. Thus in principle it is a good test reaction for micro reactors. The aim is to maximize acrolein selectivity while reducing the other by-products CO, CO2 and H2O. Propene may also react directly to give these products. The key to promoting the partial oxidation at the expense of the total oxidation is to use the CU2O phase and avoid having the CuO phase. 

GL 1] [R 1] [R 3] [P le] The performance of a typical laboratory bubble column was tested and benchmarked against the micro reactors (Figure 5.17). Using acetonitrile as solvent, the conversion of the laboratory bubble column ranged from 6 to 34% at selectivities of 17-50% [3, 38]. This corresponds to yields of 2-8%. Hence the yields of the laboratory tool are lower than those of the micro reactors, mainly as a consequence of lower selectivities. 

GL 1] [R 1] [R 3] [P le] The falling film micro reactor has a better selectivity-conversion performance than the two micro bubble columns tested (Figure 5.18) (3, 38]. The micro bubble column with narrow channels has a better behavior at large conversion than the version with wide channels. The behavior of the falling film micro reactor and the micro bubble column with narrow channels is characterized by a nearly constant selectivity with increasing conversion, while the bubble column with wide channels shows notably decreasing selectivity with conversion (similar to the laboratory bubble column). 

A single cell layer of an excised piece of onion epidermis was selected as a test object for this micro-coil, (Figure 2.1.14), and an imaging experiment was carried out, similar to the one by Mansfield et al., who used a laboratory-made micro-coil probe and gradient system [31]. Other micro-coil types, e.g., volume coils or coils that are immersed into the objects, can be adapted to specific applications and mounted on commercial imaging probes. 

The catalytic tests were carried out in a fixed bed micro-reactor at atmospheric pressure at 540 °C. The feed composition was 2.5 vol.% of propane, 5 vol. % of ammonia and 5 vol.% of oxygen. The weight of catalyst in the reactor was varied in order to keep the number of Fe ions in the reactor constant (9 pmol of Fe atoms). Conversion, selectivity and yields were calculated on the basis of mass balance in dependence on the time of stream. 

For the chemical reactor, the researchers used a nanoparticle catalyst deposited on metallic micro-structured foils. They tested Cu/ZnO and Pd/ZnO catalysts deposited on the microstructured foils. The Cu/ZnO catalyst was more active than the Pd/ZnO catalyst and had a lower selectivity to undesired carbon monoxide. However, because the Pd/ZnO catalyst was more stable, it was selected for use in their fuel processor. The Pd/ZnO carbon monoxide selectivity of the powder catalyst pressed into a pellet was lower than that of the nanoparticle catalyst deposited on the microstructured foils. This effect was attributed to contact phases between the catalyst and the metal foils. ... 

Evaluation of VOC and SVOC emission potential of individual products and materials under indoor-related conditions and over defined timescales requires the use of climate-controlled emission testing systems, so-called emission test chambers and cells, the size of which can vary between a few cm3 and several m3, depending on the application. In Figure 5.1 the dots ( ) represent volumes of test devices reported in the literature. From this size distribution they can be classified as large scale chambers, small scale chambers, micro scale chambers and cells. The selection of the systems, the sampling preparation and the test performance all depend on the task to be performed. According to ISO, chambers and cells are defined as follows ... 

In undertaking our search of the literature linked to bioanalytical assessment of solid waste leachates (Tab. 2), we circumscribed it to small-scale toxicity testing performed on leachates. Furthermore, we did not exclude marine bioassays, but we exclusively selected literature references involving test battery approaches (TBAs) on solid wastes (or their elutriates). As defined previously in the first chapter of this book, a TBA represents a study conducted with two or more tests representing at least two biotic levels. As also pointed out in Section 2 of this chapter, TBAs are suitable to assess hazard at different levels so as not to underestimate ecotoxicity. Nevertheless, we have not excluded from this review publications describing other types of bioassays (e.g., terrestrial bioassays, sub-cellular bioassays or those carried out with recombinant DNA (micro)organisms and biosensors), when those were part of the TBA. 

P 6] Peroxide testing at IMM used an H202 selective catalyst placed within a minitrickle bed reactor equipped with a micro mixer. 

The predictions of the simulations were corroborated by experimental findings. For the liquid-flow splitting unit without an additional micro device as flow resistor, a minimum/maximum flow deviation of about 6% (see Figure 4.101) was found at a low pressure drop below 10 mbar [141]. The maximum flow deviation for the liquid flow-spitting unit equipped with these six selected impinging-jet mixers amounted for initial tests to 11% (4% standard deviation) at 64-74 mbar pressure drop (see Figure 4.101). By optimization of material pretreatment and micro fabrication, a minimum/maximum deviation of the water distribution below 5% and a standard deviation below 2% were finally obtained. 

Analytical equipment that is chosen for the isolators must be selected with care. In general, select instruments that are as compact as possible that still meet the analytical needs. For most analytical testing, sample sizes will be small, so micro- or semimicrobalances are routinely used. It is recommended to place balances on vibration... 

Standard tests consisted of proximate, ultimate, higher heating value, ash composition, ash fusibility temperatures, Hardgrove grindability, and screen analyses. Special bench scale characterization tests consisted of micro-proximate analysis and micro-ultimate analysis (C, H, N) micro-proximate and micro-ultimate analyses were performed on particulate samples collected from varying stages of combustion in the DTFS and CMHF. In addition, selected samples of SRC and chars from partial combustion or pyrolysis of the SRC were submitted for Thermo-Gravimetric analyses. 

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