Dry reforming methane

Table 2 shows the initial results for the catalytic dry reforming of methane using bulk carbides of niobium, tantalum, molybdenum and tungsten, prepared by CH4 TPR. The conversions and yields obtained over P-M02C and a-WC are very similar to those predicted by thermodynamic considerations, and thus these materials are efficient catalysts for methane dry reforming. At atmospheric pressure, deactivation was observed over both catalysts after about 8 hours on stream. Examination of the post-catalytic samples by powder XRD (Figure 2) revealed that as the reaction proceeded the active P-M02C was oxidised and converted to... 

The primary cause for deactivation in current reforming catalysts, such as supported nickel, is the formation of carbon on the catalyst during reaction [20]. However, when postreaction samples of P-M02C and a-WC were examined by HRTEM, no observable carbon deposition had occurred on the catalyst surface during the reaction. In addition, activity studies demonstrated that M02C had a methane dry reforming activity similar to an active supported noble metal catalyst, namely 5% Ir/Al203 [27]. 

Results for methane dry reforming over the ternary metal carbides (C2H6 TPR T = 1223 K, p = 8 bar, GHSV = 5x10 h )... 

The preexponential factors in forward and reverse steps of reactions ri-r2 and rn were selected as adjustable based on sensitivity analysis. It was found that the estimated values deviated only slightly from the initial values estimated by transition-state theory. The kinetic data of methane steam reforming from Xu (15) and our data of methane dry reforming were used for the above adjustment. The reverse step of and forward step of r were forced to meet thermodynamic consistence (6,7). 

Sensitivity analysis indicated that no single RDS exists in methane dry reforming. Reactions ri-r3, and rr-rio were sensitive to methane conversion, while r and r were sensitive to CO2 conversion. At S/So= 0.2, the adsorption and desorption steps of CO and H2 (rio and rn) were most sensitive to methane reforming and only the reverse reaction of rg and forward reaction of rio were most sensitive to CO2 conversion. This clearly demonstrates the limitation of... 

A part from the steam reforming there are other interesting applications in the petrochemical industry methane dry reforming, catalytic partial oxidation, auto-thermal reforming, water gas shift, H2S cracking, and hydrocarbon dehydrogenation. More details about some of these applications are given in Chaps. 5, 6, 7, 8, and 9. 

One of the most important drawback related to the methane dry reforming reaction is the carbon deposition. 

Table 2.6 Methane conversion data for methane dry reforming reaction...

Gallucci F, Tosti S, Basile A (2008) Pd-Ag tubular membrane reactors for methane dry reforming a reactive method for CO2 consumption and H2 production. J Memb Sci 317 96-105... 

Catalytic carbon dioxide reforming of methane (dry reforming methane, DRM) is an excellent alternative route to obtain syngas and has received significant attention in recent years due to its scientific and industrial importance, since it converts two greenhouse gases (methane and carbon dioxide) into valuable synthesis The DRM process is industrially... 

Another problem with methane dry reforming is the formation of carbon on the surface of solid catalysts this implies a progressive reduction of the catalytic activity and a loss of reactor performance (Moulijn, Diepen, Kapteijn, 2001). The formation of solid carbon is mainly due to reactions 4.2—4.5. 

Solid catalysts for methane dry reforming in traditional and membrane reactors... 

Table 4.11 Review of the newest researches in the field of solid catalysts for methane dry reforming...

The possibility of a hydrogen removal from the reaction mixture of methane dry reforming gives the chance to reach higher conversion even at a lower temperature. This means a reduction of the energy requirement, the possibility to obtain an economic process, and a reduction of the effect of the undesired reactions. However, it is important to underline that the materials used for membrane can be expensive, so this kind of process is attractive only in the hypothesis of great performances. 

As was already said, zeolite membrane is becoming common in the field of reactor studies, so it is easy to find some examples of application in the field of methane dry reforming (Liu Au, 2001 Liu, Gao, Au, 2002). 

Despite some of the results reported above, the main theme of research, which can be found in the scientific production about membrane reactors for methane dry reforming, is based on palladium potential. Table 4.19 briefly proves this scientific trend. 

Methane dry reforming with carbon dioxide is a highly endothermic reaction that can be used for carbon dioxide and methane consumption and for the production of syngas. In particular, it can give a product with a good carbon monoxide concentration, useful for other processes. 

However, it is important to underline that methane dry reforming obviously cannot still be a total substitution of traditional routes for hydrogen production. Nevertheless, this does not mean that its study is meaningless, because it can represents a consistent... 

Horvath, A., Stefler, G., Geszti, O., Kienneman, A., Pietraszek, A., Guczi, L. (2011). Methane dry reforming with CO2 on CeZr-oxide supported Ni, NiRh and NiCo catalysts prepared by sol—gel technique relationship between activity and coke formation. Catalysis Today, 169(1), 102-111. 

Kahle, L. C., Roussiere, T., Maier, L., Herrera Delgado, K., Wasserschaff, G., Schunk, S. A., et al. (2013). Methane dry reforming at high temperature and elevated pressure impact of gas-phase reactions. Industrial and Engineering Chemistry Research, 52(34), 11920—11930. 

Nam, J.W., Chae, H., Lee, S.H., Jung, H., and Lee, K.Y. (1998) Methane dry reforming over well-dispersed Ni catalyst prepared from perovskite-type mixed oxides. Stud. Surf. Sci. Catal, 119, 843-848. 

Gonzalez, O., Lujano, J., Pietri, E., and Goldwasser, M. (2005) New Co-Ni catalyst systems used for methane dry reforming based on supported catalysts over an... 

Wang, N., Yu, X., Wang, Y., Chu, W., and Liu, M. (2013) A comparison study on methane dry reforming with carbon dioxide over LaNiOs perovskite catalysts supported on mesoporous SBA-15, MCM-41 and silica carrier. Catal Today, 212,98-107. 

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