Catalytic experimental procedure

Catalytic measurements were carried out in a stirred-bed reactor of stainless steel. The details of the reactor and experimental procedures have been described elsewhere [4]. 

Finally, experimental procedures differing from that described in the preceding examples could also be employed for studying catalytic reactions by means of heat-flow calorimetry. In order to assess, at least qualitatively, but rapidly, the decay of the activity of a catalyst in the course of its action, the reaction mixture could be, for instance, either diluted in a carrier gas and fed continuously to the catalyst placed in the calorimeter, or injected as successive slugs in the stream of carrier gas. Calorimetric and kinetic data could therefore be recorded simultaneously, at least in favorable cases, by using flow or pulse reactors equipped with heat-flow calorimeters in place of the usual furnaces. 

Acid-catalyzed photoresist films acid diffusion, 35 acid generation, 303233/341 advantages, 28 catalytic chain length, 3435r development of classes of cationic photoinitiators, 28 experimental procedure, 35-36 generation mechanism from irradiation of triphenylsulfonium salts, 28-29 merocyanine dye method for acid analysis, 30,31/33/... 

On the other hand, the method of Mukaiyama can be succesfully applied to silyl enol ethers of acetic and propionic acid derivatives. For example, perfect stereochemical control is attained in the reaction of silyl enol ether of 5-ethyl propanethioate with several aldehydes including aromatic, aliphatic and a,j5-unsaturated aldehydes, with syir.anti ratios of 100 0 and an ee >98%, provided that a polar solvent, such as propionitrile, and the "slow addition procedure " are used. Thus, a typical experimental procedure is as follows [32e] to a solution of tin(II) triflate (0.08 mmol, 20 mol%) in propionitrile (1 ml) was added (5)-l-methyl-2-[(iV-l-naphthylamino)methyl]pyrrolidine (97b. 0.088 mmol) in propionitrile (1 ml). The mixture was cooled at -78 °C, then a mixture of silyl enol ether of 5-ethyl propanethioate (99, 0.44 mmol) and an aldehyde (0.4 mmol) was slowly added to this solution over a period of 3 h, and the mixture stirred for a further 2 h. After work-up the aldol adduct was isolated as the corresponding trimethylsilyl ether. Most probably the catalytic cycle is that shown in Scheme 9.30. 

Such an involvement of an amino acid side-chain ligand switch within each catalytic cycle was a novel proposal and as such needs to be scrutinized by a variety of experimental procedures as well as analysis in the context of information known for cytochrome cd nitrite reductase from another source (see later discussion). However, it is interesting to note that something similar has been proposed for the protocate-chuate 3,4-dioxygenase enzyme from Pseudomonas putida (15). On the other hand, bacterial cytochrome c peroxidase offers an example where ligand switching seemingly relates only to an activation phenomenon. 

Catalytic hydrogenation is hardly ever used for this purpose since the reaction by-product - hydrogen chloride - poses some inconveniences in the experimental procedures. Most transformations of acyl chlorides to alcohols are effected by hydrides or complex hydrides. Addition of acyl chlorides to ethereal solutions of lithium aluminum hydride under gentle refluxing produced alcohols from aliphatic, aromatic and unsaturated acyl chlorides in 72-99% yields [5i]. The reaction is suitable even for the preparation of halogenated alcohols. Dichloroacetyl chloride was converted to dichloro-... 

Catalytic experiments were performed in a fixed bed glass tubular reactor at atmospheric pressure and at reaction temperature of 450 and 482°C for n-heptane and gas-oil, respectively. Details on the experimental procedure have already been published (7). 

For analyzing a catalytical system by the method of inverse titration one has to investigate at least 3 to 4 catalytic reactions for each chosen power of a tenth of the external metal-to-ligand ratio. To achieve this information efficiently in time, we carried out a special experimental procedure on the 1-ml scale (for experimental details see Ref. ), a flow chart is given in Scheme 3.2-1. 

Scheme 3.2-1. Flow chart of the experimental procedure for analyzing a catalytic system via the method of inverse titration ...

Pfefferle and Lyubovsky executed types of measurements that yielded critical information between active Pd phases for catalytic combustion using pure ot-alumina plates with zero porosity as a support for the catalyst. This procedure uniformly covers the plate with metal particles on the top surface where they are easily available for the reaction gases and optical analysis. This type of experimental procedure has shown that in high-temperature methane oxidation the reduced form of the supported palladium catalyst is more active than the oxidized form. The temperature at which the PdO Pd... 

Active crystal face of vanadyl pyrophosphate for selective n-butane oxidation catalyst preparation, 157-158 catalyst weight vs. butane oxidation, 162,163/ catalytic activity, 162,1 (At catalytic reaction procedure, 158 experimental description, 157 flow rate of butane vs. butane oxidation, 162,163/ fractured SiOj-CVO PjO scanning electron micrographs, 160,161/ fractured scanning electron... 

The detailed experimental procedure on the synthesis of Sn-incorporated analogues, physicochemical characterization and the catalytic POM reaction can be obtained from our earlier reports [1,2, 5]. Lattice parameters of the samples were calculated from the XRD data collected between 5 to 70° 20 employing a scan speed of 0.5° 20/min. 

In concomitance with the displacement observed by i.r., an evolution of the catalytic activity has been observed while studying the liquid-phase epoxidation of cyclohexene in the presence of (EGDA)- Mo(VI), freshly prepared or after four months of conditioning at room temperature under inert atmosphere. As usual, the appearance of epoxide was followed by gas chromatographic analyses or by direct titration of oxirane oxygen and the disappearance of hydroperoxide was monitored by iodometric titration. In figure we report concentration-time for typical runs in ethylbenzene at 80°C obtained with the experimental procedure already described (ref. 9). It may be seen that with a freshly prepared catalyst an induction period is observed which lowers the initial catalytic activity. Our modified Michaelis-Menten type model equation (ref. 9) cannot adequately fit the kinetic curves obtained due to the absence of kinetic parameters which account for the apparent initial induction period (see Figure). 

The performance and scalability of the various techniques is most easily compared in a side-by-side format. With respect to experimental procedures, it is now recognized that many chemical conversions (e.g., formation of C-N or C-C bonds) that were reported to require solid supports with catalytic activity and microwave irradiation (and thus introduced environmental concerns) do not require such auxiliaries or irradiation. They occur exothermally at low temperatures with quantitative yields and without solvent-consuming workups even on a large scale. 

Thus, with the usual experimental procedures, a comparison of conversion data as a function of space velocity (residence time) does not tell us whether the kinetics differ from first order in the region of conversion below 50% for the range of order tested (zeroth to second). On the contrary, first-order kinetics can be used to represent the conversion as a function of residence time for a wide range of situations. Some investigators have been aware of this approximate first-order behavior of integral reactors, as shown by the statement that even complex catalytic systems approximate a pseudo- first order relationship when only space velocity is varied. .. (10). 

In this report we wish to consider the initial clustering process in some detail. Are there experimental procedures which will allow more control of this growth to monomer clusters Can new metastable phases be formed and detected And do bimetallic particles formed in this way possess any unique catalytic properties ... 

Acetaldehyde decomposition, reaction pathway control, 14-15 Acetylene, continuous catalytic conversion over metal-modified shape-selective zeolite catalyst, 355-370 Acid-catalyzed shape selectivity in zeolites primary shape selectivity, 209-211 secondary shape selectivity, 211-213 Acid molecular sieves, reactions of m-diisopropylbenzene, 222-230 Activation of C-H, C-C, and C-0 bonds of oxygenates on Rh(l 11) bond-activation sequences, 350-353 divergence of alcohol and aldehyde decarbonylation pathways, 347-351 experimental procedure, 347 Additives, selectivity, 7,8r Adsorption of benzene on NaX and NaY zeolites, homogeneous, See Homogeneous adsorption of benzene on NaX and NaY zeolites... 

Li and coworkers [16] discovered that in the presence of RuCl2(PPh3)3, which is compatible with water and air, the allylic C-H bond was activated and the functional groups of homoallyl alcohols were repositioned to give allyl alcohols (Eq. 1). The experimental procedure is very simple stirring a mixture of homoallyl alcohol 1 with a catalytic amount of RuCl2(PPh3)3 in water and air at 90-100 °C for 1-3 h led to the product 2. 

The oxidation of the organic "residue" formed over the catalytic surface was performed in a conventional TPO apparatus using a 40 cm3min-l (STP) flow, of 6 mol % oxygen/helium mixture and a 5 K irtin-1 heating rate. A 5% Pd/Si02 catalyst was included in order to ensure that any CO formed was oxidized to CO2 The apparatus and complete experimental procedure were described elsewhere [18,19]. 

Testing. Studies of the catalytic activity and selectivity were conducted in a tubular unit reactor. Since this is a reactor consisting of a catalyst-packed tube of dimensions identical with those of a single tube inside a large-scale reactor, it becomes possible to reproduce the industrial conditions A thermocouple was placed in the catalyst bed, A detailed description of the experimental procedure has been presented elsewhere [4]. The tube was packed with two layers of catalyst (0.6 dm3 each). The total bed length was about 2.65 m. The feed was o-xylene of purity 98.4 wt.%. The air flow rate was 3.5 m3(STP)/h. The calcined catalyst samples were tested under conditions of continuous operation over a period of a couple of weeks during this period the concentration of o-xylene was varied from 20 to 70 g/m3(STP). 

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