Hu Xin, Skadtchenko Boris O, Trudeau Michel, Antonelli David M
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada.
J Am Chem Soc. 2006 Sep 13;128(36):11740-1. doi: 10.1021/ja0639766.
Chemically reducible micro- and mesoporous Ti oxides with controlled pore sizes from 12 to 26 A were synthesized. The hydrogen storage and adsorption capacity at 77 K was tested as a function of surface area, pore size, and reducing agent. Surprisingly, the oxidation state of the surface Ti species had an even greater effect on the storage densities than surface area or pore size. For example, the 12 A material reduced with bis(toluene) Ti possesses a surface area of less than 300 m2/g, but absorbs up to 4.94 wt % and 40.46 kg/m3 of H2 reversibly at 77 K and 100 atm. This volumetric storage capacity is higher than that of AX-21, which has a much higher surface area. The H2 binding enthalpies increased from 4.21 kJ/mol to 8.08 kJ/mol as the surface oxidation state of the Ti decreased. These results suggest that a Kubas-type sigma H2 complex may be involved and that further tuning of the H2 binding enthalpies through use of appropriate organometallic reagents may achieve even higher storage levels at more moderate temperature.
合成了孔径可控在12至26埃之间的化学可还原微孔和介孔钛氧化物。测试了77K下的储氢和吸附容量与表面积、孔径及还原剂的函数关系。令人惊讶的是，表面钛物种的氧化态对储存密度的影响甚至比表面积或孔径更大。例如，用双（甲苯）钛还原的12埃材料表面积小于300平方米/克，但在77K和100个大气压下可逆地吸收高达4.94重量%和40.46千克/立方米的氢气。这种体积储存容量高于表面积大得多的AX - 21。随着钛的表面氧化态降低，氢气结合焓从4.21千焦/摩尔增加到8.08千焦/摩尔。这些结果表明可能涉及库巴斯型σ氢配合物，并且通过使用合适的有机金属试剂进一步调节氢气结合焓可能在更适中的温度下实现更高的储存水平。
