Model feeds

Noble metals (NM) supported on carbons have been tested as catalysts for various model reactions, as well as for real feeds. In this regard, HDS, HDN, HCR and HDO activities were determined. In similar reactions, metal carbides, metal nitrides and metal phosphides supported on various forms of carbon have also been receiving attention. 

1 Noble-metal Catalysts. The unsupported TMS (from Group VI to 

Ledoux et with the aim to obtain a direct comparison of the activity of 

The activity of noble metals TMS (Rh, Ru, Pt, Pd, Ir and Re) supported on AC was drastically affected by combining with The activity was 

Noble metals supported on AC (without presulfiding) were tested as catalysts for HYD of benzene and HDS of thiophene by Guerrero-Ruiz et at a 

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In the second model (Fig. 2.16) the continuous well-stirred model, feed and product takeoff are continuous, and the reactor contents are assumed to he perfectly mixed. This leads to uniform composition and temperature throughout. Because of the perfect mixing, a fluid element can leave at the instant it enters the reactor or stay for an extended period. The residence time of individual fluid elements in the reactor varies. 

Catalyst stability studies were conducted using a variety of model feeds. The results using 0.7 wt % propionic acid in aqueous HBr demonstrate the effectiveness of operating at partial conversion to monitor deactivation. Figure 6 shows that at 292 °C, the propionic acid-contaminated feed caused rapid deactivation. Subsequent analysis of the catalyst showed carbon deposits on the catalyst. 

Commercial plastics HDPE, PP, PS and PVC in granulate form have been used as model feed. The degradation of pure polymers was followed using either at thermoanaly-tical method (MOM Derivatograph Q) or in a laboratory batch reactor system with gaschromatographic product analysis. 

Each of the detailed sub-models feed into the thermodynamic system model, and provides sizing information directly to the conceptual design and configuration. The thermodynamic system... 

Substantial effort in modelling and/or experimental measurement is required in order to derive GFFA(s) and GFFB(s). Due to errors in determining the individual transfer functions (GM(s), G 2(s), etc.), to errors in measurement, and to load variables which have not been accounted for in the models, feed-forward compensation can never be perfect, and considerable drifting of the controlled variable(s) can occur. On the other hand, the two variable feed-forward control model expressed by equation 7.165 automatically takes into account any interaction between the reflux and steam flow control loops (see also Section 7.15). 

The ability of LAB diet enhanced IFN production to regulate the Thl/Th2 responses has been thoroughly studied in animal models. Feeding OVA-primed mice with L. casei has been shown to reduce antigen-specific IgE responses in vivo (Yasui et al. 1999). A murine model of food allergy has also demonstrated that intraperito-neal administration of L. plantarum can downregulate casein-specific IgE antibody levels in vivo and IL-4 secretion as well (Murosaki et al. 1998). 

Feed model feed with pyrene and dibenzo-thiophene. 

Human lung cancer cells and human prostate cancer cells were implanted into athymic nude mice, then harvested and implanted in the lung and prostate, respectively, of a MetaMouse orthotopic model. Feeding 13-MTDA for 40 days inhibited the growth of lung cancer implants by 65% and prostate cancer implants by 85% compared to control animals (Yang et al., 2000). 

Mixtures of CO2 (5%-15%) and N2 were used as model feed gas, and monoethanolamine (ME A), diethanolamine (DEA), and 2-amino-2-methyl-l-propanol (AMP) were used as the carriers of CO2. The polyethersulfone capillary ultrafiltration membranes (see Table 13.4) were used in the module. The membrane was very stable over a discontinuous 4-month testing period. The energy consumption was found to be much smaller than those of conventional chemical absorption and membrane separation processes. 

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. 

Demelallization of Asphaltenes Modelling Feed and Product Molecular Size Dislributfons and Metal Distribution Parameters... 

DEMETALLIZATION OF ASPHALTENES MODELLING FEED AND PRODUCT MOLECULAR SIZE DISTRIBUTIONS AND METAL DISTRIBUTION PARAMETERS,... 

Composition of the standard model feed. COMPOSITION OF THE HYDROCARBON FEED... 

Organic sulphur- and nitrogen-compounds in motor fuels are a source for acid rain and harmful to the environment. Moreover, they are poisonous to the auto exhaust catalysts. To meet new developments in EU regulations on the S-concentration, a commonly applied one-step hydrodesulfurization (HDS), using conventional catalysts, e.g. C0-M0/7-AI2O3, is insufficient. A second HDS step, viz. a deep HDS step, can be more economical to reduce the S-content to the currently allowed European level of 350 ppm. This level will be reduced further to 50 ppm in 2005 [1]. In the first HDS step, often the heavy organic sulfur-containing polyaromatics survived, such as dibenzothiophene (DBT) and (4-, and/or 6-) alkylated DBTs [2,3]. They are the most refractory. In crude oils, there are also aromatic N-compounds, which suppress the performance of the HDS catalysts. Hence, a model feed for representative HDS-activity measurements should contain characteristic S- and N- compounds for practical relevance. 

Previous studies by Reinhoudt et al. [4-7] using a model feed, showed that Pd-Pt/ASA catalysts are suitable for deep HDS. It was reported that at the same total loading of Pd and Pt, the Pd/Pt atomic ratio also influences the performance [8]. Pd-Pt... 

Table 3 shows that the Pd-Pt catalysts are more active than the commercial catalysts, e.g. C0-M0/7-AI2O3, using the model feed. Although the Pd and Pt loading in our Pd-Pt/ASA catalyst is 75% higher than that used in [5] (3.5 versus 2.0 wt%), its rate constant is about twice as high. This may be partially attributed to its higher dispersion and/or to its different Pd Pt ratio (4 instead of 2) [8]. 

Linear alkyl benzene (LAB) is manufactured by catalytic dehydrogenation of C10-C13 n-parafifins, followed by alkylation with benzene. High product selectivity, and reasonable catalyst life, in the dehydrogenation reaction, are obtained at the expense of conversion, by adjusting reaction parameters. Proper choice of reaction parameters is thus of paramount importance in this reaction. The present study, was carried out with n-decane, as model feed, and a promoted Pt/ALOs catalyst. A composite Box-Wilson experimental design was adopted to develop an empirical model for predicting monoene yield as a function of reaction conditions. Further, the model was used for determination of optimum reaction parameters. 

Recently, the hydrogenation a mixture of toluene, styrene and 1-octene, representing a model feed for hydrotreating in the refining industry, was performed in monolith reactors [37]. One is a y-alumina monolith of diameter 1 cm and 15 or 30 cm long and the other is a more conventional cordierite monolith with a wall-coated layer of y-alumina. In both monoliths, the channels size is 1-2 mm and the catalyst is based on Ni. Substantial alkene conversions of more than 50% were observed in the small-channel reactors, which was attributed to the intensified mass-transfer rate generally measured in monolith reactors [16]. 

The analogue of DBT such as l,l -binaphthothiophene in the solution with decaline was used as model feed to compare the HDS activity of an AC with that of the 7-AI2O3 and a 4A molecular sieve.The experiments were conducted in the autoclave at 573 K and 5 MPa of H2. The disappearance of the model compound was followed by measuring the UV-Vis absorption at 353 nm. The results in Table 8 indicate a high activity of the AC. However, the product distribution after the experiments was not conducted. Therefore, it is not possible to determine how much of the reactant disappeared as hydrocarbon and/or hydrogenated intermediate. 

Both model compound mixtures and real feeds have been used for determining catalyst activity. Among the latter, the feeds of petroleum origin, coal-deiived liquids (CDL) and biofeeds have received attention. From the practical applications point of view, the results obtained using real feeds provide a more realistic picture on the performance of catalysts than those obtained using model compounds. For example, the effect of pore-size and pore-volume distribution on catalyst performance may not be accurately identified using model feeds. 

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