Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni,Co,Mg and Al,and their catalytic performance was investigated with dry reforming of methane.Experimental results showed that the hydrotalcite-like precursors could be completely decomposed and partly reduced by cold plasma jet,and the Nicontained catalysts exhibited much higher activity than the catalyst without Ni.Especially,the catalyst with Ni/Co ratio of 8/2 achieved not only the highest conversions of 80.3%and 69.3%for CH4 and CO2,respectively,but also the best stability in 100 h testing.The catalysts were characterized by XRD,XPS,TEM and N2 adsorption techniques,and the results showed that the better performance of the 8Ni2Co bimetallic catalyst was attributed to its higher metal dispersion,smaller metal particle size,as well as the interaction effect between Ni and Co,which were brought by the special catalyst preparation method. 相似文献
In the present research, magnesium aluminate spinel was prepared as catalyst support using a novel, facile, and efficient mechanochemical method. The Co-promoted catalysts with 20 wt.% of Ni were fabricated using an impregnation route and the samples were analyzed by the X-ray diffraction (XRD), N2 adsorption/desorption (BET), temperature-programmed reduction and desorption (H2-TPR and O2-TPD), and field emission scanning electron microscopy (FESEM) tests. The results confirmed that all samples have a mesoporous structure with a high specific surface area and the presence of cobalt caused complete CH4 oxidation at low temperatures, and no side reactions were observed. The results indicated that the 3%Co-20%Ni/MgAl2O4 catalyst was the optimal sample among the prepared catalysts, owing to the improvement of reduction features and oxygen mobility. The 50 and 90% of methane conversion was obtained at 530 and 600 °C, respectively. Also, the influence of calcination temperature, GHSV, and feed ratio was determined on the catalytic activity. The obtained outcomes revealed that the calcination temperature has a significant effect on the textural properties and catalytic efficiency. The sample calcined at 700 °C showed the weakest performance, which was related to the sintering of particles at high temperatures. The catalytic stability showed that the 3%Co-20%Ni/MgAl2O4 has acceptable stability during 600 min time of reaction.
Catalytic performances of the CO2 reforming of toluene on Co/Mg O catalysts with different cobalt loadings were evaluated in a fluidized-bed reactor. The results showed that the conversion of toluene and the stability of Co/Mg O increased, but the apparent reaction rate decreased at the initial stage with increasing the amount of metallic Co formed from the reduction of Co/Mg O catalysts at 700°C. The deactivation of Co/Mg O catalysts was mainly resulted from that a part of the metallic Co was oxidized by CO2 and could not be re-reduced by H2 at reaction temperature. Therefore, the excess metallic Co on the higher Co loading catalysts was beneficial to the catalyst stability. 相似文献
Research on Chemical Intermediates - Syngas is a very important intermediate in chemical industry for energy chemicals production through F–T synthesis. Methane steam reforming (MSR) and dry... 相似文献
Sorption enhanced steam methane reforming(SE-SMR) was performed to maximize hydrogen production and contemporary remove CO_2 from the product stream using bi-functional sorbent-catalyst compounds.Samples were tested at two different scales: micro and laboratory. The CaO amount varied in the CaO-Ca_(12)Al_(14)O_(33) sorbent system synthesized by wet mixing(CaO content of 100 wt%, 56 wt%, 30 wt%, or 0 wt% and balance of Ca_(12)Al_(14)O_(33)) which were upgraded to bi-functional compounds by impregnation of 3 wt% of Ni. Nitrogen adsorption(BET/BJH), X-Ray Diffraction(XRD), Temperature-Programmed Reduction(TPR) and Scanning and Transmission Electronic Microscopy(SEM and TEM, respectively) analyses were performed to characterize structural and textural properties and reducibility of the bi-functional materials and evaluate their catalytic behavior. A fixed sorbent composition CaO-Ca_(12)Al_(14)O_(33)(56 wt% of CaO and Ca_(12)Al_(14)O_(33) balance), was chosen to study the effect of different weight hourly space times(WHST) and CH_4 stream compositions in SE-SMR activity. Impregnated mayenite at both micro and laboratory scales showed stable H_2 content of almost 74%, with CH_4 conversion of 72% similarly to the values reported by the sample containing 30 wt% of CaO in the post-breakthrough.Sample with 30 wt% of CaO showed promisingly behavior, enhancing H_2 content up to almost 94.5%.When the sorption enhanced reaction is performed roughly 89% of CH_4 conversion is achieved, and after the pre-breakthrough, the catalyst worked at the thermodynamic level. During cycling sorption/regeneration experiments, even if CO_2 removal efficiency slightly decreases, CH_4 conversion and H_2 yield remain stable. 相似文献
Rhodium and cerium were found to be suitable additives for improving the sulfur-tolerance of Ni-based gasoline reforming catalysts.
In these cases, the Rh content was only 0.1 wt.% with 5 wt.% of Ce. The lifetime of Rh-Ce-modified Ni-based catalyst is found
to be above 600 hours at 1023K, which is over a ten times longer lifetime than that of the unmodified catalysts, when premium
gasoline was used. 相似文献
Research on Chemical Intermediates - We evaluated dry reforming of methane in a tubular fixed-bed reactor at various reaction temperatures from 923 to 973 K using different reactant... 相似文献
A series of Na-W-Mn-Zr/SiO2 catalysts promoted by different contents of S or/and P were prepared and their catalytic performance for oxidative coupling of methane was investigated to clarify the effect of S and P on the Na-W-Mn-Zr/SiO2 catalyst. The catalysts were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). From the characterization results, it is found that the addition of S and P to the Na-W-Mn-Zr/SiO2 catalyst helps the formation of active phases, such as α-cristo... 相似文献
The effect of oxidation pretreatment temperature(500 ~ 1 000 ℃) on the catalytic activity of Kovar applied on hydrocarbon CO2reforming was examined. Catalytic performance evaluation using tetradecane at 800 ℃ with 70 μmol/s CO2revealed 700 and 1 000 ℃ as the best pre-oxidation temperature in producing CO and H2,respectively. XRD and SEM-EDX analyses showed that a separate metal oxide layer composed of iron oxide(Fe2O3and F3O4),nickel,cobalt,and possibly their respective oxides started to form when oxidation was conducted at 700 ℃ or higher.The presence of iron enhanced the stability of nickel in the structure while the compact structure of Fe3O4resulted into the formation of a thick and rigid metal oxide layer on the surface of the Kovar tube. The strong physical bond between the metal oxide layer and Kovar tube provided the catalyst good mechanical strength and consequently good catalytic activity. 相似文献
Kinetics model was developed for the mixed (steam and dry) reforming of methane, which is useful for the control of H2/CO ratio. The equilibrium constants of reaction rate were determined using the experimental equilibrium data at different reaction temperatures, while the forward reaction rate constants were estimated using the experimental data under non-equilibrium (high inert fraction and high space velocity) conditions. The comparison between calculated and experimental data clearly showed that the developed model described satisfactorily, and further analysis using the parametric sensitivity determined the wall temperature and CO2 fraction in the feed gas as effective parameters for the manipulation of CH4 conversion and H2/CO ratio of synthesis gas under the equilibrium condition. Meanwhile, the inert fraction, rather than the residence time, was selected as additional parameter under non-equilibrium condition. 相似文献
CO2 reforming of CH4 over hexaaluminates LaNixMg1−xAl11O19+δ and LaNixMg0.8Al11.2−xO19+δ were studied. XRD analysis confirmed that modifier Ni as well as Mg was inlaid into the hexaaluminate lattice. Hexaaluminate
LaNixMg1−xAl11O19+δ (1.0 ≥ x ≥ 0.4) showed better catalytic activities and higher resistance to carbon deposition, which was attributed to their pure
magnetoplumbite-type structure. For this reaction, x-value between 0.6 and 0.4 was the most suitable. 相似文献
The 2-methylpyrazine was synthesized by catalytic reaction of ethylene diamine and propylene glycol at 380 ℃. The alumina supported copper catalysts with promoter were prepared by impregnation method, characterized by ICP-AES, BET and TPR. The results demonstrated that the dehydrogenation was improved by addition of chromium promoter. The selectivity of 2-methylpyrazine reached 84.75%, while the conversions of reactants were also enhanced. 相似文献
Combination of partial oxidation of methane (POM) with carbon dioxide reforming of methane (CRM) has been studied over Ru-based catalysts at 550℃.POM,CRM and combined reaction were performed over 8wt%Ru/γ-Al2O 3 and the results show that both POM and CRM contribute to the combined reaction,between which POM plays a more important role.Moreover,the addition of Ce to Ru-based catalyst results in an improvement in the activity and CO selectivity under the adopted reaction conditions.The Ce-doped catalyst was characterized by N2 adsorption-desorption,SEM,XRD,TPR,XPS and in situ DRIFTS.The mechanism has been studied by in situ DRIFTS together with the temperature distribution of catalyst bed.The mechanism of the combined reaction is more complicated and it is the combination of POM and CRM mechanisms in nature.The present paper provides a new catalytic system to activate CH4 and CO2 at a rather low temperature. 相似文献
正The electrochemical reduction of carbon dioxide(CO_2) to value-added fuels and chemicals provides a promising way to realize sustainable carbon recycling [1]. Developing robust electrocatalysts with high activity and selectivity is critically important for efficient electrochemical CO_2 reduction reaction(CO_2RR). Generally, it is challenging to achieve high efficiency and selectivity simultaneously in the CO_2RR due to the multi-proton/electron transfer processes and complex reaction intermediates. 相似文献
A series of Ce-Fe-Ox catalysts prepared by the different calcination temperatures (marked as CF-X, where X represented calcination temperature) were used to the selectivity catalytic reduction of NOx by NH3. The results explained the relationship between calcination temperature and the sulfate species over Ce-Fe-Ox, and then investigated the surface acidity and catalytic performance. The large amounts of sulfate species were formed over CF-450 and CF-550 while it was decomposed with further the increasing of calcination temperature, which resulted in the loss of surface acidity, causing a decrease in the catalytic activity over Ce-Fe-Ox. Thereby, the CF-450 catalyst showed the best catalytic activity and over 90% NOx conversion was obtained at 244–450 °C. Besides, the favored pore structure, more Fe3+ active species, higher Ce3+ concentration and the abundance of chemical adsorbed oxygen species, as well as the surface acid sites, would together contribute to the excellent catalytic activity of CF-450 catalyst. 相似文献