Desolvation and Dehydrogenation of Solvated Magnesium Salts of Dodecahydrododecaborate: Relationship between Structure and Thermal Decomposition

Attempts to synthesize solvent-free MgB_(12)H_(12) by heating various solvated forms (H_2O, NH_3, and CH_3OH) of the salt failed because of the competition between desolvation and dehydrogenation. This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). Products were characterized by IR, solution- and solid-state NMR spectroscopy, elemental analysis, and single-crystal or powder X-ray diffraction analysis. For hydrated salts, thermal decomposition proceeded in three stages, loss of water to form first hexahydrated then trihydrated, and finally loss of water and hydrogen to form polyhydroxylated complexes. For partially ammoniated salts, two stages of thermal decomposition were observed as ammonia and hydrogen were released with weight loss first of 14 % and then 5.5 %. Thermal decomposition of methanolated salts proceeded through a single step with a total weight loss of 32 % with the release of methanol, methane, and hydrogen. All the gaseous products of thermal decomposition were characterized by using mass spectrometry. Residual solid materials were characterized by solid-state 11B magic-angle spinning (MAS) NMR spectroscopy and X-ray powder diffraction analysis by which the molecular structures of hexahydrated and trihydrated complexes were solved. Both hydrogen and dihydrogen bonds were observed in structures of [Mg(H_2O_6B_(12)H_(12)]⋅6 H_2O and [Mg(CH_3OH)_(6)B_(12)H_(12)]⋅6 CH_3OH, which were determined by single-crystal X-ray diffraction analysis. The structural factors influencing thermal decomposition behavior are identified and discussed. The dependence of dehydrogenation on the formation of dihydrogen bonds may be an important consideration in the design of solid-state hydrogen storage materials

Final Report for "Investigation of reaction networks and active sites in bio-ethanol steam reforming over Co-based catalysts" with all publications attached.

This was a university-based research project in support of distributed reforming production technologies for hydrogen. Our objective was to examine the steam reforming of bio-ethanol and other related bio-derived liquids over non-precious metal catalyst systems to enable small-scale distributed hydrogen production technologies from renewable sources. The study targeted development of a catalytic system that does not rely on precious metals and that can be active in the 350-550 C temperature range, with high selectivity and high stability. To this end, we adopted a multi-prong research strategy, that included catalyst formulation and synthesis, detailed catalyst characterization, reaction kinetics and reaction engineering, molecular modeling and economic analysis studies. Our approach was an iterative one, where the knowledge gained in one aspect of the study was utilized to modify and fine-tune catalyst development. The research addressed many fundamental and inter-related phenomena involved in the catalytic steam reforming of ethanol that may not be readily studied in an industrial development setting. The outcome of the project was a catalytic system that was able to meet the DOE targets in hydrogen production, with high H{sub 2} yield, high selectivity and stability that could perform efficiently in the 350-550 C temperature range. In addition, we were able to answer many fundamental questions about the catalytic systems that could easily be translated to other catalytic systems. The study resulted in 14 refereed journal articles, with one more in preparation. The results were also shared broadly at many different national and international forums such as conferences of the American Chemical Society, American Institute of Chemical Engineers, North American Catalysis Society, International Congress on Catalysis and International Conference on Catalysis for Renewable Sources. There were 30 presentations given at various national and international meetings. The P.I. was also invited to give 11 lectures on the findings from this study at many universities and research centers in the USA and other countries. The knowledge base acquired through this study is expected to bring industry closer to designing catalytic systems that can be tailored for the specific hydrogen production applications, especially for distributed hydrogen production strategies

Final Report for "Investigation of reaction networks and active sites in bio-ethanol steam reforming over Co-based catalysts" with all publications attached.

This was a university-based research project in support of distributed reforming production technologies for hydrogen. Our objective was to examine the steam reforming of bio-ethanol and other related bio-derived liquids over non-precious metal catalyst systems to enable small-scale distributed hydrogen production technologies from renewable sources. The study targeted development of a catalytic system that does not rely on precious metals and that can be active in the 350-550 C temperature range, with high selectivity and high stability. To this end, we adopted a multi-prong research strategy, that included catalyst formulation and synthesis, detailed catalyst characterization, reaction kinetics and reaction engineering, molecular modeling and economic analysis studies. Our approach was an iterative one, where the knowledge gained in one aspect of the study was utilized to modify and fine-tune catalyst development. The research addressed many fundamental and inter-related phenomena involved in the catalytic steam reforming of ethanol that may not be readily studied in an industrial development setting. The outcome of the project was a catalytic system that was able to meet the DOE targets in hydrogen production, with high H{sub 2} yield, high selectivity and stability that could perform efficiently in the 350-550 C temperature range. In addition, we were able to answer many fundamental questions about the catalytic systems that could easily be translated to other catalytic systems. The study resulted in 14 refereed journal articles, with one more in preparation. The results were also shared broadly at many different national and international forums such as conferences of the American Chemical Society, American Institute of Chemical Engineers, North American Catalysis Society, International Congress on Catalysis and International Conference on Catalysis for Renewable Sources. There were 30 presentations given at various national and international meetings. The P.I. was also invited to give 11 lectures on the findings from this study at many universities and research centers in the USA and other countries. The knowledge base acquired through this study is expected to bring industry closer to designing catalytic systems that can be tailored for the specific hydrogen production applications, especially for distributed hydrogen production strategies

In situ DRIFTS characterization of wet-impregnated and sol-gel Pd/TiO 2 for NO reduction with CH4

The adsorption/desorption behavior of 2%Pd/TiO2 catalysts synthesized by wet-impregnation and modified sol–gel techniques were examined in NO–CH4–O2 reaction using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The catalyst prepared by the modified sol–gel method showed significantly higher resistance toward oxygen while maintaining a 100% NO conversion. Under NO+CH4+O2 flow, the main adsorbed NO species was identified as the linearly adsorbed NO on metallic palladium (Pd0–NO) at high temperatures. On the oxidized sample, the major NO species was found to be a bridged nitrate species. Pd0–NO species was suggested to react with CHx to form surface NHx species. Over the sol–gel catalyst, the peak intensity for Pd0–NO species was much higher than that over the impregnated catalyst. The DRIFTS data seem to suggest that this species could play a role in reduction of NO with CH4 over Pd/TiO2 catalysts

Characterization and temperature-programmed studies over Pd/TiO2 catalysts for NO reduction with methane

Characterization and temperature-programmed studies were performed over Pd/titania catalysts to examine their activity in the reduction of NO with methane. The catalyst was prepared using a wet impregnation technique and Pd-acetate was used as a precursor for palladium. Techniques such as BET surface area measurements, X-ray diffraction, laser Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy were used for the characterization of the catalyst before and after the reaction. Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) were also used to probe the surface to understand its adsorption/desorption characteristics and reducing capabilities. The results obtained from these studies together with the reaction investigations have given some important insight into the functionality of this catalyst