SO4^2—／ZrO2的相结构和超强酸性及其对丁烷异构化反应的催化活性

通过沉淀、回流和掺杂等方法制备了ZrO2呈四方相及单斜相的SO4^2-／ZrO2（SZ），并用XRD，TEM，低温N2－BET和吡啶吸附IR等技术定量测量地测定和探讨了SZ的结构特征和表面超强酸性及其对丁烷异构化反应的催化活性，结果表明，ZrO2呈单斜相结构的SZ表面Broensted（B）酸与Lewis（L）酸的浓度比B]/L]较ZrO2以四方相为主的SZ高约40％，但其对丁烷异构化反应的比催化活性则较后者低约31％，由掺Mg^2 所制备的ZrO2呈四方相的SMZ具有与ZrO2呈纯单斜相的SZ非常接近的B]/L]比，且表现出比末掺Mg^2 的ZrO2以四方相为主的SZ更高的比催化活性，从催化剂晶结构对表面B酸浓度及强度影响的角度进行了讨论。

Crystal Structure and Acidity of Solid Acid SO_4~(2-)/ZrO_2 and Its Catalytic Activity for Isomerization of Butane

Sulfated zirconia (SZ) samples with different crystal phases were prepared via precipitation, doping and refluxing in an open system. The structural, textural, and acidic features of the as prepared solid acids have been quantitatively characterized by means of XRD, TEM, N 2 BET and IR after pyridine adsorption. The catalytic activity of the catalyst samples for butane isomerization was investigated in a static reactor. It was shown that the ratio of Brnsted acid concentration to Lewis acid concentration on the surface of monoclinic SZ is about 40% greater than that on the suface of tetragonal dominated SZ, while the specific activity of the former for butane isomerization is 31% lower than that of the latter. Additionally, the Mg doped and stabilized tetragonal SZ demonstrated a high / value close to that of monoclinic SZ and higher catalytic activity than any other aforesaid forms of SZ. The relatively lower catalytic activity of monoclinic SZ is likely derived from its weaker strength of Brnsted acid site. As to Mg stabilized SZ(SMZ), the substituting Mg for Zr will generate negative charge defects, which inevitably absorb protons as the compensative species. Thus high concentration of Brnsted acid on the surface of SMZ is expected and this seems to account for its excellent performance in butane isomerization.