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1.
The C–C bond-breaking step of pentene adsorbed on a model zeolite cluster is examined using ab initio and density functional theory (DFT/B3LYP) electronic structure techniques as an example of the β-scission process that arises in cracking of alkanes and alkenes. After pentene has been protonated by the acid site, the reactant for the cracking process corresponds to a pentyl cation covalently bound to the oxygen of the zeolite, ZO −–C 5H +11. The product of the C–C bond-breaking process is propene plus an ethyl cation bound to a neighboring oxygen. The energy of the transition state relative from B3LYP calculations is 60 kcal/mol relative to the pentyl cationic reactant. For the case of the branched olefin methyl pentene, the transition state energy is slightly lower (55 kcal/mol), but the overall reaction energy is essentially the same as for pentene. The results are compared to the case of the gas phase pentyl carbenium ion. 相似文献
2.
The reduction of nitrogen oxides by propene in the presence of air under net oxidising conditions has been studied for two Cu/alumina catalysts of low (1%) and high (5%) copper loadings in a flow microreactor and by DRIFT. The reaction was studied in the range 473–773 K using mixtures of 2.5% NO, 1% C 3H 6 and 10% O 2 with a balance of nitrogen or helium, using samples which were pretreated in air at 673 K and also over samples which had been pre-exposed to SO 2 at 473 K. The surface species present under reaction conditions have been identified and the sensitivity of their adsorption sites in the two different loaded catalysts to SO 2 pre-treatment has been investigated. SO 2 adsorption enhanced NO adsorption at 473 K in the absence of oxygen and, in reaction, enhanced formation of NCO species leading to increased levels of adsorbed CO as a decomposition product. 相似文献
3.
Catalytic cracking of butene to propene and ethene was investigated over HMCM-22 zeolite. The performance of HMCM-22 zeolite was markedly influenced by time-on-stream (TOS) and reaction conditions. A rapid deactivation during the first 1 h reaction, followed by a quasi-plateau in activity, was observed in the process along with significant changes in product distributions, which can be attributed to the fast coking process occurring in the large supercages of MCM-22. Properly selected reaction conditions can suppress the secondary reactions and enhance the production of propene and ethene. According to the product distribution under different butene conversion, we propose a simple reaction pathway for forming the propene, ethene and by-products from butene cracking. HMCM-22 exhibited similar product distribution with the mostly used high silica ZSM-5 zeolite under the same conversion levels. High selectivities of propene and ethene were obtained, indicating that the 10-member ring of MCM-22 zeolite played the dominant role after 1 h of TOS. However, MCM-22 exhibited lower activity and stability than that on high silica ZSM-5 zeolite with longer time-on-stream. 相似文献
4.
Molybdenum impregnated HZSM-5 zeolite catalysts with MoO 3 loading from 1 to 8 wt.% were studied in detail for the selective catalytic reduction (C 2H 2-SCR) of NO by acetylene. A 83.9% of NO could be removed by the reductant at 350 °C under 1600 ppm of NO, 800 ppm of C 2H 2 and 9.95% of O 2 in He over 2%MoO 3/HZSM-5 catalyst with a specific activity of in NO elimination and the competitiveness factor (c.f.) of 33.6% for the reductant. The NO elimination level and the c.f. value were ca. 3–4 times as high as those using methane or propene as reductant over the catalyst in the same reaction condition. About same reaction rate was estimated in NO oxidation as that in the NO reduction over each xMoO 3/HZSM-5 ( x = 0–8%) catalyst, which confirms that NO 2 is a crucial intermediate for the aimed reaction over the catalysts. Appropriate amount of Mo incorporation to HZSM-5 considerably enhanced the title reaction, both by accelerating the intermediate formation and by strengthening the adsorption NO x on the catalyst surface under the reaction conditions. Rather lower adsorption tendency of acetylene compared with propene on the catalysts explains the catalyst's steady performance in the C 2H 2-SCR of NO and rapid deactivation in the C 3H 6-SCR of NO. 相似文献
5.
The distribution of gaseous products and the nature of the surface species generated during the selective catalytic reduction of NO with C 3H 6 in the presence of excess O 2 (i.e. C 3H 6-SCR) were studied over both a 0.4% Co/γ-Al 2O 3 catalyst and a sulphated 1.2% Ag/γ-Al 2O 3 catalyst. The results were compared with those previously reported for the C 3H 6-SCR over 1.2% Ag/γ-Al 2O 3 and γ-Al 2O 3. High concentrations of NO 2 were observed in the product stream of the SCR reaction over the 0.4% Co/γ-Al 2O 3 and sulphated 1.2% Ag/γ-Al 2O 3 materials. The results show that (as in the case of the γ-Al 2O 3 and also probably that of the 1.2% Ag/γ-Al 2O 3) the NO 2 was formed via an alternative route to the direct oxidation of NO with O 2. The yields of NO 2 were higher over the Co/γ-Al 2O 3 than over the other materials and in contrast to the other materials, no NH 3 was produced over the Co/γ-Al 2O 3 catalyst. Based on these results and those of in situ DRIFTS experiments, a global reaction scheme incorporating organo-nitrogen species as key intermediates is proposed. In this scheme, NO, propene and oxygen react to form organo-nitro and/or organo-nitrito adsorbed species, the reaction products of which combine to yield N 2. The results reported here suggest that Co preferentially promotes the formation of nitrito-compounds which can readily decompose to NO 2, whereas Ag preferentially promotes the formation of nitro-compounds (from reaction of strongly bound ad-NO x species) which can decompose to isocyanates and ammonia. The sulphation of the 1.2% Ag/γ-Al 2O 3 reduced the surface concentration of strongly bound ad-NO x species which were thought to react with the reductant or derived species to yield the organo-nitrogen species. 相似文献
6.
The reaction mechanism and the rate-determining step (RDS) of the isomerisation of n-alkanes (C 4–C 6) over partially reduced MoO 3 catalysts were studied through the effects of the addition of an alkene isomerisation catalyst (i.e. CoAlPO-11). When an acidic CoAlPO-11 sample was mechanically mixed with the MoO 3, a decrease of the induction period and an increase of the steady-state conversion of n-butane to isobutane were observed. These data support previous assumptions that a bifunctional mechanism occurred over the partially reduced MoO 3 (a complex nanoscale mixture of oxide-based phases) during n-butane isomerisation and that the RDS was the skeletal isomerisation of the linear butene intermediates. The only promotional effect of CoAlPO-11 on the activity of partially reduced MoO 3 for C 5–C 6 alkane hydroisomerisation was a reduction of the induction period, as the RDS at steady-state conditions appeared to be dehydrogenation of the alkane in this case. However, lower yields of branched isomers were observed in this case, the reason of which is yet unclear. 相似文献
7.
The alcohol decomposition and olefin hydrogenation on the hydrogen-treated Ni ion-exchanged (exchange degree, 30%) potassium niobate (Ni-K 4Nb 6O 17) were performed. Formation of propene from i-propanol on Ni-K 4Nb 6O 17 was much smaller than that observed on bulk Nb 2O 5, while the olefin yields from ethanol and n-propanol were almost the same on both catalysts. The 1- butene hydrogenation did not proceed on Ni-K 4Nb 6O 17, whereas propene hydrogenation took place rapidly on the same catalyst at 80°C. The formation of the acid sites and Ni metallic sites by hydrogen treatment at 300 °C was proposed by using temperature-programmed reduction (TPR) and extended X-ray absorption fine structure (EXAFS). These results suggest that Hg2-treated Ni-K4Nb6O17 acts as a shape selective acid- and metal-catalyst at suitable reaction temperatures. 相似文献
8.
A series of HZSM-5 zeolites modified by different amounts of phosphorus (P/HZSM-5) were prepared. The physicochemical features of P/HZSM-5 catalysts were characterized by means of XRD, BET, NH 3-TPD, FT-IR spectra of adsorbed pyridine, etc., and their performances for the catalytic cracking of the mixed C 4 alkanes to produce light olefins were investigated. The results indicated that phosphorus (P) modification not only modulated the amount of acidic sites and the percentage of weak acidic sites in total acidic sites, but also regulated the acid type, i.e., the ratio of L/B (Lewis acid/Brönsted acid). The introduction of P also altered the basic characteristics of HZSM-5 which was evidenced by CO 2-TPD analysis. Consequently, P modification with suitable amount was favorable for enhancing the selectivity to light olefins, especially to propene. At the temperature of 650 °C, the maximum yields of propene and ethene were achieved 25.6 and 33.9%, which were higher than those over parent HZSM-5 by 7 and 4.5%, respectively. Aromatics yield was found to be decreased with the increasing P loading due to the reduction of strong acid and the formation of new basic site which inhibited the hydrogen transfer reaction. All this indicates that P-modified HZSM-5 zeolites are effective catalysts for the cracking of mixed C 4 alkanes to produce more light olefins. 相似文献
9.
Effect of additives, In 2O 3, SnO 2, CoO, CuO and Ag, on the catalytic performance of Ga 2O 3–Al 2O 3 prepared by sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. As for the reaction in the absence of H 2O, CoO, CuO and Ag showed good additive effect. When H 2O was added to the reaction gas, the activity of CoO-, CuO- and Ag-doped Ga 2O 3–Al 2O 3 was depressed considerably, while an intensifying effect of H 2O was observed for In 2O 3- and SnO 2-doped Ga 2O 3–Al 2O 3. Of several metal oxide additives, In 2O 3-doped Ga 2O 3–Al 2O 3 showed the highest activity for NO reduction by propene in the presence of H 2O. Kinetic studies on NO reduction over In 2O 3–Ga 2O 3–Al 2O 3 revealed that the rate-determining step in the absence of H 2O is the reaction of NO 2 formed on Ga 2O 3–Al 2O 3 with C 3H 6-derived species, whereas that in the presence of H 2O is the formation of C 3H 6-derived species. We presumed the reason for the promotional effect of H 2O as follows: the rate for the formation of C 3H 6-derived species in the presence of H 2O is sufficiently fast compared with that for the reaction of NO 2 with C 3H 6-derived species in the absence of H 2O. Although the retarding effect of SO 2 on the activity was observed for all of the catalysts, SnO 2–Ga 2O 3–Al 2O 3 showed still relatively high activity in the lower temperature region. 相似文献
10.
Direct syntheses of hydrocarbons from CO 2 hydrogenation were investigated over hybrid catalysts consisting of methanol synthesis catalyst (CuZnOZrO 2) and zeolites (MFI and SAPO). The yield of hydrocarbons was strongly depending upon the amount of zeolite's acid sites as measured by NH 3 TPD, while the product distributions were hardly affected by the change of acidity. The main product was ethane in the case of MFI hybrid catalyst and C 3 or C 4 hydrocarbon in the case of SAPO hybrid catalyst. This difference in product distribution was attributed to different mechanism of hydrocarbon formation. Investigation based on the ethene co-reaction suggested that the consecutive mechanism operated for HZSM-5 and the carbon pool mechanism for SAPO. 相似文献
11.
Methylation of toluene (in one case benzene) with methanol has been investigated over four different zeolites: Small and large crystal ZSM-5, dealuminated mordenite and zeolite beta. The feed ratio methanol/arene was varied over a wide range, mostly >1, using nitrogen or helium as carrier gas. A rather high space velocity was employed (WHSV (methanol + arene): 5–35 h −1). The reaction temperature was 350°C or 375°C. A parallel set of experiments was performed using 13C methanol (99% 13C). The products were analyzed by on-line gas chromatography using a GC–MS system allowing determination of isotopic composition of the more important products, i.e., ethene, propene and the arenes when 13C methanol was employed, otherwise a FID was used. The goal was to obtain mechanistic information, and no attempt has been made to optimize for any particular reaction product. The experiments showed that ethene and propene were isotopically mixed, containing 50–75% 13C. The 25–50% 12C atoms coming from the reactant arene. Over all catalysts the arene was, when fed alone, essentially inert with 0.5% or less conversion, giving neither ethene nor propene in measurable quantities. The isotopic distribution in ethene was indistinguishable from a random distribution. Propene, although being close to, displayed some deviation from randomness. The 12C/13C isotopic ratio in propene was equal to that in ethene, and they both varied with the methanol/arene ratio in the feed, but much less so than the variation in feed composition. The results support a pool mechanism where the catalytic activity for converting methanol to hydrocarbons is connected with the presence of adsorbates in the zeolite cavities which add methanol and split off product molecules, notably ethene and propene. Formation of ethene by reaction between C1 species is at best a minor reaction. While formation of propene may take place by a homologation/cracking mechanism, this route was of minor importance here. Polymethylbenzenes which were formed in many cases displayed a pronounced isotopic scrambling, containing up to six 13C atoms in the benzene ring. Molecules with fewer 13C atoms than the number of added methyl groups were also identified. 相似文献
12.
The mechanism of the NO/C 3H 6/O 2 reaction has been studied on a Pt-beta catalyst using transient analysis techniques. This work has been designed to provide answers to the volcano-type activity behaviour of the catalytic system, for that reason, steady state transient switch (C 3H 6/NO/O 2 → C 3H 6/Ar/O 2, C 3H 6/Ar/O 2 → C 3H 6/NO/O 2, C 3H 6/NO/O 2 → Ar/NO/O 2, Ar/NO/O 2 → C 3H 6/NO/O 2, C 3H 6/NO/O 2 → C 3H 6/NO/Ar and C 3H 6/NO/Ar → C 3H 6/NO/O 2) and thermal programmed desorption (TPD) experiments were conducted below and above the temperature of the maximum activity ( Tmax). Below Tmax, at 200 °C, a high proportion of adsorbed hydrocarbon exists on the catalyst surface. There exists a direct competition between NO and O 2 for Pt free sites which is very much in favour of NO, and therefore, NO reduction selectively takes place over hydrocarbon combustion. NO and C 3H 6 are involved in the generation of partially oxidised hydrocarbon species. O 2 is essential for the oxidation of these intermediates closing the catalytic cycle. NO 2 is not observed in the gas phase. Above Tmax, at 230 °C, C 3H 6 ads coverage is negligible and the surface is mainly covered by O ads produced by the dissociative adsorption of O 2. NO 2 is observed in gas phase and carbon deposits are formed at the catalyst surface. From these results, the state of Pt-beta catalyst at Tmax is inferred. The reaction proceeds through the formation of partially oxidised active intermediates (CxHyOzNw) from C 3H 6 ads and NO ads. The combustion of the intermediates with O 2(g) frees the Pt active sites so the reaction can continue. Temperature has a positive effect on the surface reaction producing active intermediates. On the contrary, formation of NO ads and C 3H 6 ads are not favoured by an increase in temperature. Temperature has also a positive effect on the dissociation of O 2 to form O ads, consequently, the formation of NO 2 is favoured by temperature through the oxygen dissociation. NO 2 is very reactive and produces the propene combustion without NO reduction. These facts will determine the maximum concentration of active intermediates and consequently the maximum of activity. 相似文献
13.
On an anodic alumina supported silver catalyst with a low Ag loading (1.68 wt.%), NO x (NO/He, NO/O 2/He, NO 2/He) adsorption measurements and NO x-temperature programmed decomposition (TPD)/temperature programmed surface-reaction (TPSR) measurements in different gas streams (He, C 3H 6/He, C 3H 6/O 2/He) were conducted to investigate the formation, consumption and reactivity of surface adsorbed NO x species. During NO adsorption, no noticeable uptake of NO was detected. Introducing oxygen greatly improved the formation of ads-NOx species. A greater quantity of surface nitrate species was found after NO2 adsorption, accompanied with gaseous NO release. The result of TPSR demonstrates the surface nitrate species can be effectively and preferentially reduced by propene. When introducing oxygen into the propene gas stream of TPSR test, the significantly increased amount of reacted nitrate undoubtedly shows the importance of oxygen in activating propene. The pathway for the selective reduction of NOx in the presence of excess oxygen is proposed to pass through the selective reduction of the adsorbed nitrate species with the activated propene. The enhanced NOx conversion when replacing NO with NO2 was attributed to the stronger NOx adsorption capacity and oxidation ability of NO2, than those for NO. With increasing oxygen concentration, the difference between NO and NO2 would gradually decrease, and finally disappear in a high excess of oxygen. 相似文献
14.
The reaction mechanism of the reduction of NO by propene over Pd-based catalysts was studied by FTIR spectroscopy. It was observed that the reaction between NO and propene most probably goes via isocyanate (2256–2230 cm −1), nitrate (1310–1250 cm −1) and acetate (1560 and 1460 cm −1) intermediates formation. Other possible intermediates such as partially oxidized hydrocarbons, NO 2, and formates were also detected. The reaction between nitrates and acetates or carbonates reduced nitrates to N 2 and oxidized carbon compounds to CO 2. In situ DRIFT provides quick and rather easily elucidated data from adsorbed compounds and reaction intermediates on the catalyst surface. The activity experiments were carried out to find out the possible reaction mechanism and furthermore the kinetic equation for NO reduction by propene. 相似文献
15.
氟胺类物质是最有希望作为哈龙替代品的含氮化合物之一,全氟三乙胺作为典型的氟胺类物质具有良好的灭火效果。为研究全氟三乙胺热解机理,在管式加热炉内对全氟三乙胺进行热分解,通过GC-MS分析全氟三乙胺在不同温度条件下的热解产物,并用Gaussian软件对其热解反应路径进行理论计算。结果表明:保持停留时间为10 s,全氟三乙胺的初始热解温度为600℃,750℃完全热解,热解产物有C 4F 9N、C 3F 7N、C 2F 6和C 3F 8,热解温度较低时C 4F 9N体积分数最大,热解温度较高时C 3F 7N体积分数最大。在全氟三乙胺热解反应路径计算中,全氟三乙胺分子中的C—C键断裂后存在1条反应路径,可生成实验产物中的C 3F 8;全氟三乙胺分子的C—N键断裂后存在3条反应路径,可生成实验产物中的C 3F 7N、 C 4F 9N和C 2F 6。全氟三乙胺热解后产生的CF 3自由基可与H、OH自由基发生反应,从而产生灭火作用。此外,其热解产物C 4F 9N和C 3F 7N具有CN双键,更容易与燃烧活泼自由基·OH、·H发生化学作用,对研究全氟三乙胺的灭火机理具有十分重要的意义。 相似文献
16.
Oxidation of propene and propane to CO 2 and H 2O has been studied over Au/Al 2O 3 and two different Au/CuO/Al 2O 3 (4 wt.% Au and 7.4 wt.% Au) catalysts and compared with the catalytic behaviour of Au/Co 3O 4/Al 2O 3 (4.1 wt.% Au) and Pt/Al 2O 3 (4.8 wt.% Pt) catalysts. The various characterization techniques employed (XRD, HRTEM, TPR and DR-UV–vis) revealed the presence of metallic gold, along with a highly dispersed CuO (6 wt.% CuO), or more crystalline CuO phase (12 wt.% CuO). A higher CuO loading does not significantly influence the catalytic performance of the catalyst in propene oxidation, the gold loading appears to be more important. Moreover, it was found that 7.4Au/CuO/Al2O3 is almost as active as Pt/Al2O3, whereas Au/Co3O4/Al2O3 performs less than any of the CuO-containing gold-based catalysts. The light-off temperature for C3H8 oxidation is significantly higher than for C3H6. For this reaction the particle size effect appears to prevail over the effect of gold loading. The most active catalysts are 4Au/CuO/Al2O3 (gold particles less than 3 nm) and 4Au/Co3O4/Al2O3 (gold particles less than 5 nm). 相似文献
17.
氟胺类物质是最有希望作为哈龙替代品的含氮化合物之一,全氟三乙胺作为典型的氟胺类物质具有良好的灭火效果。为研究全氟三乙胺热解机理,在管式加热炉内对全氟三乙胺进行热分解,通过GC-MS分析全氟三乙胺在不同温度条件下的热解产物,并用Gaussian软件对其热解反应路径进行理论计算。结果表明:保持停留时间为10 s,全氟三乙胺的初始热解温度为600℃,750℃完全热解,热解产物有C 4F 9N、C 3F 7N、C 2F 6和C 3F 8,热解温度较低时C 4F 9N体积分数最大,热解温度较高时C 3F 7N体积分数最大。在全氟三乙胺热解反应路径计算中,全氟三乙胺分子中的C—C键断裂后存在1条反应路径,可生成实验产物中的C 3F 8;全氟三乙胺分子的C—N键断裂后存在3条反应路径,可生成实验产物中的C 3F 7N、 C 4F 9N和C 2F 6。全氟三乙胺热解后产生的CF 3自由基可与H、OH自由基发生反应,从而产生灭火作用。此外,其热解产物C 4F 9N和C 3F 7N具有CN双键,更容易与燃烧活泼自由基·OH、·H发生化学作用,对研究全氟三乙胺的灭火机理具有十分重要的意义。 相似文献
18.
Selective catalytic reduction of NO x (SCR-NO x) with decane, and for comparison with propane and propene over Cu-ZSM-5 zeolite (Cu/Al 0.49, Si/Al 13.2) was investigated under presence and absence of water vapor. Decane behaves in SCR-NO x like propene, i.e. the Cu-zeolite activity increased under increasing concentration of water vapor, as demonstrated by a shift of the NO x–N 2 conversion to lower temperatures, in contrast to propane, where the NO x–N 2 conversion is highly suppressed. In situ FTIR spectra of sorbed intermediates revealed similar spectral features for C 10H 22– and C 3H 6–SCR-NO x, where –CH x, R–NO 2, –NO 3−, Cu +–CO, –CN, –NCO and –NH species were found. On contrary, with propane –CH x, R–NO 2, NO 3−, Cu +–CO represented prevailing species. A comparison of the in situ FTIR spectra (T–O–T and intermediate vibrations) recorded at pulses of propene and propane, moreover, under presence and absence of water vapor in the reaction mixture, revealed that the Cu 2+–Cu + redox cycle operates with the C 3H 6–SCR-NO x reactions in both presence/absence of water vapor, while with C 3H 8–SCR-NO x, the redox cycle is suppressed by water vapor. It is concluded that decane cracks to low-chain olefins and paraffins, the former ones, more reactive, preferably take part in SCR-NO x. It is concluded that formation of olefinic compounds at C 10H 22–SCR-NO x is decisive for the high activity in the presence of water vapor, while water molecules block propane activation. The increase in NO x–N 2 conversion due to water vapor in C 10H 22–SCR-NO x should be connected with the increased reactivity of intermediates. These are suggested to pass from R–NO x → –CN → –NCO → NH 3; the latter reacts with another activated NO x molecule to molecular nitrogen. The positive effect of water vapor on the NO x–N 2 conversion is attributed to increased hydrolysis of –NCO intermediates. 相似文献
19.
The catalytic behaviour of SiO 2 supported MoO 2 and V 2O 5 catalysts in the partial oxidation of methane to formaldehyde with O 2 (MPO) in the range 400–800°C has been investigated by temperature programmed reaction (TPR) tests. Both the sequence of the onset temperature of product formation and the product distribution patterns signal that MPO on silica based oxide catalysts occurs mainly via a consecutive reaction path: CH 4 → HCHO → CO → CO 2. At T >/ 700°C a parallel surface assisted gas-phase reaction pathway leads to the formation of minor amounts of C 2 products both on SiO 2 and MoO 3/SiO 2 catalysts. The redox properties of MoO 3/SiO 2 and V 2O 5SiO 2 catalysts have been systematically evaluated by H 2 and CH 4 temperature programmed reduction (H 2-TPR, CH 4-TPR) measurements. H 2-TPR results do not account for the reactivity scale of oxide catalysts in the MPO. CH 4-TPR measurements indicate that the enhancement in the specific activity of the silica is controlled by the capability of MoO 3 and V 2O 5 promoters in providing ‘active’ lattice oxygen species. 相似文献
20.
Alkali halide added transition metal oxides produced ethylene selectively in oxidative coupling of methane. The role of alkali halides has been investigated for LiCl-added NiO (LiCl/NiO). In the absence of LiCl the reaction over NiO produced only carbon oxides (CO 2 + CO). However, addition of LiCl drastically improved the yield of C 2 compounds (C 2H 6 + C 2H 4). One of the roles of LiCl is to inhibit the catalytic activity of the host NiO for deep oxidation of CH 4. The reaction catalyzed by the LiCl/NiO proceeds stepwise from CH 4 to C 2H 4 through C 2H 6 (2CH 4 → C 2H 6 → C 2H 4). The study on the oxidation of C 2H 6 over the LiCl/NiO showed that the oxidative dehydrogenation of C 2H 6 to C 2H 4 occurs very selectively, which is the main reason why partial oxidation of CH 4 over LiCl/NiO gives C 2H 4 quite selectively. The other role of LiCl is to prevent the host oxide (NiO) from being reduced by CH 4. The catalyst model under working conditions was suggested to be the NiO covered with molten LiCl. XPS studies suggested that the catalytically active species on the LiCl/NiO is a surface compound oxide which has higher valent nickel cations (Ni (2+δ)+ or Ni 3+). The catalyst was deactivated at the temperatures>973 K due to vaporization of LiCl and consumption of chlorine during reaction. The kinetic and CH 4---CD 4 exchange studies suggested that the rate-determining step of the reaction is the abstraction of H from the vibrationally excited methane by the molecular oxygen adsorbed on the surface compound oxide. 相似文献
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