Application Of Characterization Of Solid Surface Acidity/Basicity With Microcalorimetric Technique

The number and intension of surface acids and bases are very important parameters when characterizing surface Acidity/Basicity of solid Catalyst. At present, we can acquire the related information by lots of methods, such as TPD, indicator Hamett, IR-Py and microcalorimetric adsorption technique. However, of which,only using the last one can measure the number and intension of surface acid/base sites,quantificationally. Thus, microcalorimetric adsorption technique is useful for characterization of surface Acidity/Basicity of solid Catalyst. We can acquire lots of information to conclude the activity of catalyst, such as the properties of adsorption force, the types of adsorption bond, the reciprocity between degree of consistency and adsorption molecule on the surface of solid, and the intension and number of catalyst activity sites by both measuring and studying microcalorimetric adsorption. Therefore, the data of microcalorimetric adsorption are very important to not only the preparation, characterization and screening of catalyst but also the discussion of it's mechanism.The microcalorimetric adsorption equipment in this study is established with the help of doctor Shen, Nanjing University, recently. The system is composed of vacuum part and microcalorimetric adsorption part. We can measure differential heat and adsorptive capacity using it, respectively. We perform 1-2μmol sample adsorpted per time using right probe molecule at the optimal temperature, and stop until the sample adsorption is saturated. Finally, we can find that the capacity of microcalorimetric adsorption is changed following the degree of coverage and acquire the information which is about intensity distribution of adsorption centers on the surface of catalyst. In the present study, I operate the quantitive characterization of acidity and basicity sites on the surface of solids using microcalorimetric technique mainly: I have found that that the sites of acidty and basicity are distributed uniformly on the surface of Zn_xCo_1-xCr₂O₄, the strong acid L number is the biggest, meanwhile, there are also a few of the strongest base sites from the microcalorimetric adsorption characterization of Zn_xCo_1-xCr₂O₄ series catalyst. The optimum ratio of Zn and Co is 1. From the acid-base analysis of Zn_xCo_1-xCr₂O₄ series Catalyst using microcalorimetric adsorption technique, we find that the activity sites of ortho alkylation reaction of phenol and methyl alcohol on the suface of Zn_xCo_1-xCr₂O₄ series catalyst should be formed by synergic action. Because there are enough methanol, and carbon ions are provided by a number of bases, the character of strong acid L can determine activities of ortho alkylation reaction of phenol and methyl alcohol (conversion, selectitity and yield).The microcalorimetric adsorption experimental results of solid amine resin A, solid amine resin B and NH₂-SBA-15 show that solid amine resin A is one of CO₂ absorbing agents, which can be used longly. Comparing with solid amine resin A, the repetitive utilization ratio of solid amine resin B can be arrived at 97%. Moreover, the CO2 adsorbability of solid amine resin B is better, and the repetitive utilization ratio of the base cores is higher. In addition, comparing with NH₂-SBA-15, the acid /base cores of the two solid amine resins are distributed uniformly and closely, the number is bigger, the CO₂ adsorbability is stronger and the distribution of base sites on surface is more reasonable. The number of solid amine resin base core is higher than which of NH₂-SBA-15 shows that the former has advantages of CO2 adsorbability.It is set forth the microcalorimetric adsorption quantitative analysis of acidity and basicity sites of different samples. The results show that microcalorimetric adsorption technique is one of the important methods of catalyst characterization. It is useful to measure the acidity/basicity quantificationally. Moreover, it also can serve as an inspection method of catalyst condition screening.The innovation of the thesis is that the quantitive data of acidity/basicity sites on the suface solid have been measured accurately using microcalorimetric adsorption technique.