Catalyst activity test procedure

The catalyst samples which were subjected to sintering and activity-testing procedures were also characterized by X-ray diffraction and STEH/EOX techniques The average noble metal crystallite size and composition are reported in this paper. 

In a typical procedure, benzene was stirred with freshly activated catalyst sample. Prior to activation, the catalyst samples were ground and sieved, and a fraction of 315-800 pm was used for each catalytic activity test. Catalyst samples were activated by heating in an oven at 185T for 2 h prior to catalyst activity tests. An aliquot of bcn/yl chloride was then added and the reaction mixture stirred for 15 min at room temperature. Mass ratios of the reactants and catalyst were benzyl chloridc/catalyst = 10 and bcn/cne/benzyl chloride = 3.5-4. An excess of benzene resulted in the formation of diphenylmethane as the dominant product. The follow ing reactions occur in the system ... 

Establish procedures for testing and verification of catalyst activity and identification including use testing. Include procedure to monitor shelf life of catalyst to maintain activity... 

The extension of this work to include catalyst particles with internal voids is more complex, as there are regions of catalytic activity adjacent to the internal holes, complicating the testing procedure. A comparison of several different catalyst configurations of internal voids has recently been completed, and a description of the method, its verification, and the results obtained will be the subject of a future publication. 

This paper gives an example of the response of one equilibrium catalyst to the three basic Demet procedures and to modified versions of these procedures. The catalysts are evaluated by elemental analysis and by their cracking performance, as determined by the micro activity test (MAT). 

Cracking performance. Micro activity test results for the different preparations are given in Table II. Variants of all three basic Demet procedures (see Fig. 1-3) can be used to improve the performance of this equilibrium catalyst. 

The Microsimulation test (MST). Modification of the operating procedure and experimental conditions of a convential micro activity test (MAT) has led to the so-called microsimulation test (MST, see Figure 3). Basically, the reactor is a fixed bed with transient operation during the catalyst contact time. A complete description of the operation and design of the MST reactor is given by O Connor in (11). Table I gives an overview of the main differences between the MR and the MST. 

A test procedure is to be developed for measuring the activity of various catalysts. A small, fixed-bed reactor is available in the laboratory. The same gaseous reaction will be used to evaluate each catalyst. The method of analysis of the product stream is fairly accurate but not good enough to justify differential reactor operation. Hence the sample of any catalyst tested will be sufficient in amount to obtain conversions above 30%. The feed rate, temperature, pressure, feed and effluent composition (or conversion), and mass of catalyst in the reactor will be routinely measured. The activity will be defined as the ratio of a measurable variable for any catalyst to the value of that variable for a standard catalyst. The variable chosen should be a true measure of the intrinsic rate of the reaction at a catalyst site. ... 

The preparation of Ru supported catalysts by sol-gel method, indeed, was extended to obtain new formulations by changing the type of support. Alkali-promoted Ru/MgO systems were prepared starting from magnesium ethoxide, Ru3(CO)i2 and a cesium compound [9]. The gels were subjected to an activation/reduction procedure to substantially obtain Ru-CsOH/MgO and then tested as catalysts in the ammonia synthesis at atmospheric pressure. It was evidenced that the sol-gel prepared Cs-promoted Ru/MgO catalysts are much more active, under similar reaction comlitions, than the analogous catalysts prepared by the impregnation procedures reported in literature [10]. 

Table 16. Major differences between vehicle and the engine test procedures used to measure the activity of emission control catalysts.

The activity tests of liquid-phase oxidation of aqueous phenol solution were conducted in a semibatch slurry reactor at operating conditions given in the caption of Figure 1. The experimental apparatus, the procedure of these measurements and the analysis of the reaction samples are described in detail in a preceding paper [6]. Additional kinetic and mechanistic investigations were carried out in an isothermal, differentially operated "liquid-saturated" fixed-bed reactor [8, 9] which was packed with a pretreated EX-1144.3 catalyst (Sfld-Chemie... 

Cerium-, copper-cerium coexchanged ZSM-5, copper-MCM-22, copper- and cerium-EMT type zeolite, copper-FAU type zeolite and copper-Beta exhibit an activity of the same order as that of copper-ZSM-5 in NOx reduction under simulated Diesel exhaust conditions. Propene was used as the reducing agent. The catalysts were used in a powder form and their activities tested in a fixed-bed flow reactor at a space velocity of 50 000 H . Copper-SAPO-34 and cerium- and gallium-EMT type zeolite have a moderate activity under the same conditions. The presence of water vapor inhibits the activity of EMT-zeolites. When an ageing procedure is carried out on copper-EMT type zeolite, dealumination occurs. The increase of the Si/Al ratio of the zeolite does not limit the dealumination process. The exchange of the zeolite with lanthanum prevents the zeolite from dealumination but leads to a loss of the catalytic activity. 

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