Catalyst evaluation

A. A. Lemonidou and co-workers, "Catalyst Evaluation and Kinetic Study for Ethylene Production," paper presented atMIChE SpringNational... 

M. J. Heim rich and M. L. DeViney, Eean NO Catalyst Evaluation and Charactericyation, SAE 930736, Society of Automotive Engineers, Warrendale, Pa., 1993. 

Characterizing FCC feed provides quantitative and qualitative csti mates of the FCC unit s performance. Process modeling uses the feed properties to predict FCC yields and product qualities. The process model should be used in daily unit monitoring, catalyst evaluations, optimization, and process studies. 

Shinnar, R. and Feng, C. A., Structure of complex catalytic reactions thermodynamic constraints in kinetic modeling and catalyst evaluation, I EC Fundam., 24, 153-170 (1985). 

We compared Pt/silica-alumina, yttria-modified silica-alumina, and fluorided alumina for n-Ci2 isomerization. Not surprisingly, increasing yttria content lowers catalyst activity at a fixed space velocity (Fig. 10). The 9% Y203/Si-Al catalyst compares closely to the 1%F/Al203 catalyst in activity. Of the catalysts evaluated here, the 9%Y203-loaded Si-Al had higher isomerization selectivity at equal conversion (Fig. 11). 

Of the catalysts prepared on different activated carbon snpports. Catalyst A was found to be the most active and most selective catalyst for the hyam reaction. However, this catalyst had the poorest lllterability of the catalysts evaluated. Catalyst F had good activity, but the lowest in this study, and had excellent filtration properties. A direct correlation between hyam activity and filtration rate was found (Figure 10.1). 

Scheme 7 Rh-catalyzed reaction and arrayed catalyst evaluation...

In a typical experiment, 50 g of NaOH flakes were first dissolved in 120 g of water. The required amount of catalyst was then wet loaded into the caustic solution and 72 g of ethanolamine added. Before heating the autoclave was closed and the air inside purged out with N2. The autoclave was then heated with the set temperature (433 K) reached after about 80 minutes. This time is taken as zero in the plots that follow. The standard operating conditions used for catalyst evaluation unless otherwise stated were as follows temperature 433 K pressure 0.9 MPa ethanolamine concentration 2.9 M NaOH concentration 6.2 M stirrer speed 80 rpm catalyst 8 g with particle size 106-211 pm. 

It is well known that acrylates undergo transition metal catalyzed reductive aldol reaction, the silanes R3SiH first reacting in a 1,4 manner and the enolsilanes then participating in the actual aldol addition.57,58 A catalytic diastereoselective version was discovered by arrayed catalyst evaluation in which 192 independent catalytic systems were screened on 96-well microtiter plates.59 Conventional GC was used as the assay. A Rh-DuPhos catalyst turned out to be highly diastereoselective, but enantioselectivity was poor.59... 

The palladium-catalyzed asymmetric allylic substitution using seven different phosphano-oxazoline ligands at various ligand-to-metal ratios was also studied.112 An aluminum block containing 27 wells was placed in a dry box in which the reactions were carried out in parallel. Analyses were performed by conventional chiral GC equipped with an autosampler. Such a setup allowed about 33 catalyst evaluations per day. Apparently, only a few dozen were carried out in the study, resulting in the identification of a catalyst showing an ee-value of 74% in the reaction of 4-acyloxy-2-pentene with malonate.112 It is not clear whether further ligand diversification would lead to catalysts more selective than the record set in this case by the Trost-catalyst (92% ee).113... 

Schlatter, J. C. Sinkevitch, R. M. Mitchell, P. J. "A Laboratory Reactor System for Three-Way Catalyst Evaluation" GM Research Publication GMR-2911 presented at 6th N. Amer. Mtg. Catal. Soc., Chicago, IL, March 1979. 

A colloidal suspension prepared according to the method described in Section 13.2.3 was contacted with a porous alumina carrier to obtain a bimetallic palladium-tin catalyst. Evaluation of the catalytic properties of this system is detailed... 

SILC was also used without covalently anchoring the ionic liquid fragment to the silica support. In this case, [bmim][PF6] was simply added to silica in acetone together with the catalyst. [Rh(norbornadiene)(PPh3)2]PF6 and the solvent evaporated to yield the supported catalyst-philic phase. Catalyst evaluation on the hydrogenation of model olefins showed enhanced activity in comparison to homogeneous and biphasic reaction systems, in analogy to Davis s observations. Also... 

With both approaches, it is key to establish the current regions where samples are under kinetic control to allow the correct comparison. Many reported comparisons of catalysfs in MEA sfrucfures point to differences in performance, which are attributed to intrinsic catalyst differences when it is clear that differences are due to mass fransport effects because of catalyst layer structure. To help overcome these difficulties, it is recommended that, for catalyst evaluation, pure reactants be used (e.g., O2 instead of air) and at relatively high stoichiometries. Use of current-voltage curves should be corrected for elecfrolyte or membrane resistances and Tafel analysis used to identify fhe kinefically confrolled current regions. 

Note for Guidance on Specification Limits for Residues of Metal Catalysts, Evaluation of Medicines for Hiunan Use (2002) The Emopean Agency for the Evaluation of Medicinal Products, London, http //www.emea.en.int... 

In attempting to optimize a catalyst of this kind, many factors and parameters must be balanced one against another. Operating factors are also so complex that catalyst evaluation becomes extremely complex and costly. Literally hundreds of catalyst preparations and countless evaluations were undertaken before arriving at a final catalyst for manufacture. 

Several different reactor types were used for catalyst evaluation, including a DCR pilot riser [3] an ACE fixed fluidized bed (FFB) reactor [7], a Riser simulator [4,9], and a specially designed extended residence time circulating pilot unit. The reaction conditions of each of the reactors will be reported in the sections dealing with the specific reactor type. Different grades of Brazilian Campos Basin derived VGOs were used in the experiments. Feed properties are presented in Table 2.1. 

The authors would like to thank Petrobras for permission to publish this paper and the technicians from the catalyst preparation, catalyst evaluation, and gas chromatography laboratories at CENPES and Professor Sedran s group at INCAPE/ CONICET-EIQ/UNL, Santa Ee, Argentina for their contributions. 

Catalyst Evaluation Using an ARCO Pilot Unit on North Sea Atmospheric Residue... 

Advance Catalyst Evaluation unit (ACE) [5] was used to study catalyst-feed interactions on two commercially available, laboratory deactivated catalyst materials. 

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