Mordenite catalyst

Selective synthesis of ethylenediamine from ethanolamine over modified H-mordenite catalyst... 

The synthesis of ethylenediamine (EDA) from ethanolamine (EA) with ammonia over acidic t3pes of zeolite catalyst was investigated. Among the zeolites tested in this study, the protonic form of mordenite catalyst that was treated with EDTA (H-EDTA-MOR) showed the highest activity and selectivity for the formation of EA at 603 K, W/F=200 g h mol, and NH3/ =50. The reaction proved to be highly selective for EA over H-EDTA-MOR, with small amounts of ethyleneimine (El) and piperazine (PA) derivatives as the side products. IR spectroscopic data provide evidence that the protonated El is the chemical intermediate for the reaction. The reaction for Uie formation of EDA from EA and ammonia required stronger acidic sites in the mordenite channels for hi er yield and selectivity. 

The fluoride-treated acidic mordenite catalysts have, in fact, the triple advantages of ... 

Figure 2 Benzene alkylation with C10-Ci4 paraffin dehydrogenate MF, using fluorinated mordenite catalyst M, using the non-fluorinated mordenite precursor.

Table 2 Benzene alkylation with 1-dodecene, fluorided mordenite catalysts.

Initial inner acid sites isomerization selectivity is low for 10MR zeolites and high for Mordenite catalysts. This suggests that large 12MR channels of Mordenite are favorable to EB isomerization into xylenes in the zeolite microporosity. 

H(hydrogen)-mordenite catalyst The crystallites were approximate parallelepipeds, the long dimension of which was assumed to be the pore length. Their analysis was based on straight, parallel pores in an isothermal crystallite (2 faces permeable). They measured (initial) rates of dehydration of methanol (A) to dimethyl ether in a differential reactor at 101 kPa using catalyst fractions of different sizes. Results (for two sizes) are given in the table below, together with... 

To test this hypothesis a Pt/mordenite catalyst was prepared from H-mordenite by exchanging a small amount of Pt and reducing at low temperature, so that Pt-H adducts could be formed and most Pt atoms were located in the side pockets of the... 

In the second step, the crude ethylene plus benzene are passed over a silica mordenite catalyst at 650—700° F and atmospheric pressure to produce EB at 91% selectivity and 23% ethylene conversion. 

Kumar, N., Villegas, J.I., Salmi, T., Murzin, D.Y., and Heikkila, T. (2005) Isomerization of n-butane to isobutane over Pt-SAPO-5, SAPO-5, Pt-H-morden-ite and H-mordenite catalysts. Catal. Today, 100, 355-361. 

Allain, J.F., Magnoux, P., Schulz, P., and Guisnet, M. (1997) Hydroisomerization of n-hexane over platinum mazzite and platinum mordenite catalysts kinetics and mechanism. 

Guisnet, M. and Eouche, V. (1991) Isomerization of n-hexane on platinum dealuminated mordenite catalysts II. Kinetic study. Appl. Catal, 71, 295-306. 

Both ethene and propene can diffuse into the channels of a particular mordenite catalyst used for hydrogenation. Explain why only ethane is produced. 

To prepare noble metal on H-mordenite catalysts the noble metal ammino complex-containing material is normally heated in air using staged heating (21, 22, 23, 24). In Ref. 24 the calcination of Pt(NH3)4-NH4 mordenite is discussed in detail, and it is shown that during calcination in air at about 300° C a strongly exothermic reaction occurs, presumably a result of the oxidation of NH3. Data are presented on the influence of calcination conditions on platinum dispersion. 

Catalysts Based on Mordenite. Isomerization of paraffins over H-mordenite based catalysts has been described (6, 7,14, 0, 21). Minachev (7) reports that cyclohexane isomerization activity of Na-H-mordenite catalysts increases linearly with H+ concentration in the zeolite for 25-94% exchange. He further observed that H-mordenite is deactivated by other cations such as Li, K, Mg, Cd, Zn, and Al. This agrees with Bryant s work (6) he reported that, compared with Pd-H-mordenite, samples in which hydrogen was partly replaced by Ca or Zn had an appreciably lower n-pentane isomerization activity. 

Table II. Hydroisomerization of n-Pentane Influence of Silica-Alumina Molar Ratio of Activity of Pd-H-Mordenite Catalysts...

The major results of this study are consistent with a simple picture of mordenite catalysts. An increase in effective pore diameter, whether by extraction or exchange, will increase the rate of transport of reactant and product molecules to and from the active sites. However, aluminum ions are necessary for catalytic activity as aluminum is progressively removed by acid extraction, the number of active sites and the initial activity decrease. Coke deposition is harmful in two ways coke formation as the reaction proceeds will cause a decrease in effective pore diameter and effective diffusivity, and coke deposited on active sites will result in a chemical deactivation as well. 

Specimens of catalysts (0.125 gram) were deactivated at 360° C for desorption experiments by using continuous (rather than pulsed) operation. Purified liquid benzene or cumene was pumped to the injection port of the microreactor system with a syringe pump at the rate of 0.00241 moles/hour. Propylene was fed from a gas lecture bottle through a rotameter at a rate of 0.00245 moles/hour. Parent H-mordenite catalyst samples were de-... 

Andreu et ah (11) explained the increased activity (with increasing alumina content of amorphous silica-alumina catalysts) for cracking of sec-butylbenzene by the greater density of acid sites in the high-alumina-content catalysts. Adams et ah (12) proposed that the interaction of several active sites with reactant molecules in mordenite catalysts was partly responsible for the rapid rate of activity loss. 

Figures 1 and 2 show the abundance of the aliphatic and olefinic ion series (CnH2n+i)+ and (CnH2n-i)+, respectively, that resulted from deactivated parent H-mordenite catalysts at temperature conditions near 360°C. Desorption temperature precision was approximately 4°C. While reproducibility results are not shown, agreement was obtained between the results of duplicate desorption tests on separate samples of the same catalyst batch and the curves given in Figures 1, 2, and 3.

Bertea, L. E., Kouwenhoven, H. W. and Prins, R. Vapor-phase nitration of benzene over modified mordenite catalysts, Appl. Catal., A, 1995, 129, 229-250. 

R Mantha.S.Bathia.M.S.Rao Kinetics of Deactivation In Methylation of Toluene over H-ZSM-5 and Hydrogen Mordenite Catalysts itKtEng.Chem.Res. 30 (1991) 281... 

Fig. 4A, B C show the activity change of mordenite catalysts as a function of copper content on catalyst for the reduction of NO with the sulfur content deposited on catalyst surface. Note that catalytic activity was defined as the ratio of the reaction rate for a deactivated catalyst to that for a fresh catalyst based on the first-order reaction kinetics a = k/k. The effect of sulfur compounds deposited on the catalysts due to the presence of S02 in the feed gas stream on SCR activity significantly depends on both the reaction temperatures and the copper content of the catalyst. For HM catalyst, the catalytic activity varies with its sulfur content depending on reaction temperatures, i.e., an exponential relationship at 250 °C and a linear relationship at 400 DC as shown in Fig.4A. It has already been investigated that the surface area of deactivated HM catalyst exponentially decreases with sulfur content at lower temperature of 250 °C, while it linearly decreases at higher temperature of 400 aC as shown in Fig. 1 A. Judging from these results between catalytic activity and surface area with their catalyst sulfur content at two different reaction temperatures, the decline of the catalytic activity for deactivated HM catalyst occurs simply due to the decrease of surface area.

The formation of ammonium salts is equilibrium process, which depends on the concentration of NH v S03 and reaction temperature. The higher concentration of NH3 and S03 favors the formation of these ammonium salts at a given temperature. Therefore, the formation of ammonium salts on catalyst surface seems to largely depend on the catalytic activity of mordenite catalysts for S02 oxidaion to SO and thus S03 concentration over the... 

By means of ion exchange using metal cations of different size and specific charge, the geometrical restrictions, the number and the strength of the Bronsted acid sites, as well as the adsorption properties of the zeolite material can be influenced. Investigations of this kind have been reported in the literature, for example for ZSM-5 and mordenite catalysts [20, 105]. 

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