Thermal analysis catalysts evaluation

A. Garforth, S. Fiddy, Y. H. Lin, A. G. Siakhali, P. N. Sharratt, and J. Dwyer, Catalytic Degradation of High Density Polyethylene an Evaluation of Mesoporous and Microporous Catalysts using Thermal Analysis, Thermochim. Acta, 294, 65-69 (1997). 

The first catalytic evaluation was performed using thermal analysis which gave the onset decomposition temperature and the exothermicity of the reaction. The DTA results of both supports and catalysts are given in Fig. 3. The features are in agreement with previous work ° they present a weak endothermic peak corresponding to water evaporation followed by a strong exothermic peak attributed to the catalytic decomposition (Fig. 1 profile a). In the absence of catalyst the thermal decomposition occurs at 160 Both supports exhibit similar profile with broadened endothermic peaks due to water vaporization and... 

Abstract. After a brief introduction on zeolite constitution, structure and properties, the suitability of thermal analysis in characterizing the zeolite materials and in investigating their potential behavior in different application fields is analyzed. Kinetics and thermodynamics of water desorption, thermal stability, phase transformations, occluded phase decomposition and gas evolution, structure collapse and recrystallization, change in electrical properties, all in relation to thermal treatments, are the specific subjects reviewed. Use of thermal analysis in the evaluation of zeolite content in multicomponent mixtures and in the characterization of zeolite catalysts are the two additional main topics discussed. 

The basic strength or alkalinity of the catalyst (H ) will be estimated using Hanunet titration or Hammet indicators. Thermal decomposition of the catalyst is evaluated by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). FT-IR analysis is also carried out to record the absorption peaks for further characterization of the catalysts. All these characterization techniques are normally used for base catalysts and the same has been reported in the literature, which is shown in the tables mentioned in the present chapter. 

The thermal analysis and calorimetric techniques provide a very large variety of possibilities of experimentations, of combinations with other analytic techniques that make unlimited the number of applications, especially in the field of characterization of catalysts and evaluation of catalytic processes. 

The powdered catalysts were evaluated in an integral continuous fixed bed reactor (Ig cat, total gas flow rate 6 1/h), with on line gas analysis by gas chromatogral using both thermal conductivity detector and flame ionization detector. 

The analysis of adsorption, electronic, mechanical, and thermal properties of CNTs and CNFs, with respect to catalytic requirements, is needed to evaluate their stability and to predict how the metallic particles could anchor to the support and how the reagents could interact with these metal-supported catalysts, and to understand what such novel carbon forms could bring to catalysis. The possibility of nanofilamentous carbon shaping and sizing to prevent handling problems is also discussed. 

DeNOx - Scope of the model analysis was to evaluate on a quantitative basis the effective dependence of the intrinsic activity of the monoliths on the thermal sintering, and separate it from the contributions of inter-phase mass transfer and the effect of morphological modifications on intra-porous diffusion. When excess ammonia is present, as in the case of the experiments herein analyzed, then the Ealy-Rideal kinetic expression which is contained in the model of the SCR reactor reduces to a first order dependence on NO concentration under such conditions, an unique adaptive parameter, kc, accounts for the DeNOx intrinsic activity. Estimation of kc for the three calcined catalysts was obtained by fitting the model to each set of experiments. Input data included the operating conditions, the geometrical... 

Crystalline zirconium phosphate was prepared by the method described by Clearfield and Thakur. Thermal activation was carried out at 100, 200, 300, 400 C. A portion of the amorphous material used to make the crystalline zirconium phosphates was retained for evaluation. Catalysts were characterised using titrimetric methods to measure acidity and x-ray diffraction to examine crystallinity. Thermogravimetric analysis (TGA) was used to determine phase changes on heat treatment. 

Figure 11.19 shows the process flow sheet for a pilot-scale fluidized bed gasifier, capable of processing some 20 kg/h of biomass feed, coupled with a thermal cracker and reformer reactor. The reformer is loaded with fluidizable nickel-based reforming catalyst and fitted with gas analysis ports at its inlet and outlet. The system has been used to evaluate catalyst activity and the decay of hydrocarbon conversion with time from a slip stream sample of the raw fuel gas. In this way, it is possible to quantify the frequently reported phenomenon of commercial catalyst deactivation, sometimes quite rapid, from high activity of fresh samples to lower residual activity brought about by various factors, including the presence of poisons (sulphur, chlorine) and coke formation. 

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