SO2 ADSORPTION USING CuO/?-Al2O3 ADSORBENT IN FIXED BED REACTOR

• Main Author: Bahrin, David
• Format: Dissertations
• Language: Indonesia
• Subjects: Teknik kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/33404
• Institution: Institut Teknologi Bandung

ABSTRACT SO2 ADSORPTION USING CuO/?-Al2O3 ADSORBENT IN FIXED BED REACTOR By David Bahrin NIM: 33012001 (Doctoral Program in Chemical Engineering) As the Indonesian coal contains sulphur in the range of 0.1% to 9.8%, the coal powered steam power plant may potentially emit SO2 above the allowed threshold limit. Desulphurization using metal oxide based adsorbent or a mixture of metal oxide, such as CuO/?-Al2O3 presents the potential for development. This technique is advantageous due to the relative ease in production, large SO2 adsorption capacity and the regenerability that allows for multiple usage. The support material used is the commercial ?-Al2O3 support produced by the Laboratorium Teknik Reaksi Kimia dan Katalisis, Institut Teknologi Bandung with the following parameters; 1) specific surface area of 218.43 m2/g, 2) pore volume of 0.46 cm3/g, and 3) pore diameter of 83.33 Å. The target in this research dissertation is to obtain CuO/?-Al2O3 adsorbent with good characteristics and high performance in SO2 adsorption through the manufacture and characterization of CuO/?-Al2O3 adsorbent at several Cu concentration, evaluating the CuO/?-Al2O3 adsorbent performance, that includes the SO2 adsorption capacity and the adsorption time required to achieve saturated condition, with change in Cu metal concentration and process temperature (Topic-1). The Cu metal was deposited on ?-Al2O3 support using dry impregnation method and the SO2 adsorption was performed on fixed bed reactor. Fixed bed reactor configuration was chosen due to ease of operation. The regenerability test of the saturated CuO/?-Al2O3 adsorbent was performed to restore the SO2 adsorbing capability of the adsorbent (Topic-2). CuO/?-Al2O3 adsorbent used correspond to the adsorbent with the best performance according to the experimental results from Topic-1. The regeneration method of saturated CuO/?-Al2O3 adsorbent used was the thermal decomposition method as this method does not necessitates the extra cost incurred in the purchase of reductant and this method also does not necessitates Cu oxidation after regeneration. The regeneration of CuO/?-Al2O3 adsorbent was performed at 500, 600 and 700?C, with air flowrate of 1-3 mL/s with the regeneration time of 20, 40 and 60 minutes. The adsorption-regeneration cycle was repeated for 10 times. The characterization of CuO/?-Al2O3 adsorbent used involves the determination of pore characteristics and crystal types formed on the adsorbent that has went through the repeated process of adsorption-regeneration with the aim to analyze the effect of regeneration on adsorbent performance. viii Experiments in the topic-1 and topic-2 used model gas in the form of SO2 gas mixture and moisture-free air with concentrations of 4600-21,000 ppmv or 13,150-60,000 mg/Nm3. The feed gas flow rate of 1.4-1.8 mL/sec or 84-108 mL/min and the amount of the initial adsorbent was 0.4 g and 1 g. In the experimental topic-3, SO2 concentration of the model gas was similar to the SO2 concentration of the gas obtained from coal combustion with sulfur content of about 1.2% weight (air dry base), that is 680 ppmv or 2500 mg/Nm3. The feed gas flow rate on experiment in topic-3 is 1.21 L/min. The performance of the CuO/?-Al2O3 adsorbent was examined from the change in SO2 concentration in the reactor outlet gas or from the breakthrough curve. Appropriate model and kinetic parameters can be applied to predict the breakthrough curve in the SO2 adsorption process using the CuO/?-Al2O3 adsorbent. The target of this research (topic-3) is to interpret the experimental result obtained from SO2 adsorption using CuO/?-Al2O3 adsorbent using the model developed by previous researcher in which the experimental condition was similar but the SO2 concentration was much lower. The result of the study are the parameters of the model such as the overall reaction rate constant (kr), CuO consumption rate constant (kd), activation energy (Ea) and collision factor (A). The preparation of CuO/?-Al2O3 adsorbent by dry impregnation method with Cu(NO3)2 solution as source of Cu metal is reproducible. The dry impregnation method has successfully dispersed the CuO active phase well on the support surface for adsorbents with Cu concentrations less than or equal to 8%w of the adsorbent. The amount of CuO active phase attached to the support has a significantly affect the change in pore properties (specific surface area and pore volume) of CuO/?-Al2O3 adsorbent. The length of time required for the adsorbent to achieve saturated condition increases with increase in the process temperature and tends to be the same at varying Cu concentration.CuO/?-Al2O3 adsorbent with an active phase amount of about 8%w of adsorbent and applied at 450?C (adsorption temperature) has the largest adsorption capacity, that is 3.71 g sulfur/100 g adsorbent. Regeneration using thermal decomposition method can significantly restore the CuO/?-Al2O3 adsorbent from saturated condition. Regeneration of the saturated CuO/?-Al2O3 adsorbent at temperature of 600?C results in the highest average adsorption capacity up to the 10th adsorption-regeneration cycle. The SO2 adsorption capacity of the used adsorbent at all temperature tends to decrease up to the 10th adsorption-regeneration cycle with the largest drop on the adsorbent that was regenerated at 500?C. The adsorbent regeneration by thermal decomposition especially at regeneration temperature of 500?C cannot restore the pore structure of the used adsorbent to initial condition and this indicates the presence of CuSO4 compounds or Al2(SO4)3 compounds that has yet to be decomposed. Al2(SO4)3 compounds formed on the 8Cu adsorbent regenerated at 500?C on the adsorption-regeneration cycle of about 10 times, The regeneration of adsorbent at 700?C up to the adsorption-regeneration cycle of 10 times affects ix the change in pore structure of the 8Cu adsorbent and this indicates that there was change in the adsorbent pore structure. The model ????????,????????????,????=????????????[?????????????????????????????(?????????????)] with ????????=27.862????????????(?20,33????????) and ????????=0,024????????????(?6,64????????) is suitable when used to depict the breakthrough curve of SO2 adsorption using the CuO/?-Al2O3 adsorbent in fixed bed reactor. Validation of the models and kinetic modeling parameters at the experiments with the other sum of adsorbents (2 and 4 grams) yield satisfactory results. The model and kinetic modeling parameters mentioned can be used to predict the breakthrough curve of the SO2 adsorption using CuO/?-Al2O3 adsorbent in a fixed bed reactor at lower SO2 concentration in the feed that is 2500 mg/Nm3 (860 ppm) when the type of adsorbent, operating condition such as the temperature and pressure are the same. Keywords: SO2 adsorption, CuO/?-Al2O3 adsorbent, characterization, modeling parameters, fixed bed reactor, regeneration, validation