Breakthrough analysis of H2S removal on Cu-V-Mo, Cu-V, and Cu-Mo mixed oxides

Kinetic studies carried out for the sorption of H2S in the presence and absence of hydrogen on Cu-V-Mo, Cu-V, and Cu-Mo mixed oxides gave detailed information about the reaction sequences. Formation of SO2 even in the presence of hydrogen at the initial stages of the sorption process showed the partial reduction of the metal oxides prior to the sulfidation step. A sorption experiment carried out with Cu-Mo mixed oxide gave incomplete sulfidation of molybdenum, whereas with Cu-V mixed oxide complete sulfidation was obtained. Predictions of the breakthrough curves by the deactivation model showed good agreement with the experimental results

Activities of copper oxide and Cu-V and Cu-Mo mixed oxides for H2S removal in the presence and absence of hydrogen and predictions of a deactivation model

Considering the importance of high-temperature removal of H2S from industrial gases, sorption studies were carried out on copper oxide and Cu-V and Cu-Mo mixed oxides in the absence and presence of hydrogen in a fixed-bed reactor. Experiments were carried out in a wide temperature range between 300 and 700 degreesC. A significant amount of SO2 was produced with CuO sorbent in the absence of hydrogen. In the case of mixed oxide sorbents, SO2 formation was detected even in the presence of hydrogen. On the basis of the experimental concentration profiles of H2S, SO2, and H2O measured in the reactor effluent and XRD results for the solid products, reaction sequences were proposed in reducing (in hydrogen) and nonreducing atmospheres. A deactivation model proposed for such noncatalytic gas-solid reactions gave excellent predictions of the H2S breakthrough curves. Sorption rate parameters obtained in the absence of hydrogen were found to be larger than the corresponding values in the presence of hydrogen. Partial reduction of CuO prior to the sorption of H2S in the presence of hydrogen is the major reason for this observation

Removal of hydrogen sulfide by clinoptilolite in a fixed bed adsorber

Due to its toxic and corrosive nature, H2S should be safely removed from the gases produced in gasification or combustion processes. In this study, adsorption of hydrogen sulfide was investigated on a natural zeolite, namely clinoptilolite. H2S adsorption characteristics of Western Anatolian clinoptilolite was studied in a fixed-bed system at different temperatures between 100 and 600 degreesC at atmospheric pressure. H2S adsorption capacity of clinoptilolite was found to be about 0.03 g S/g clinoptilolite at 600 degreesC. A deactivation model considering concentration dependence of activity term was applied to experimental results and adsorption rate constant and activation energy values were evaluated. Good agreement of the experimental breakthrough curves with the model predictions was observed

Mn-Cu and Mn-Cu-V mixed-oxide regenerable sorbents for hot gas desulfurization

Porous Mn-Cu and Mn-Cu-V mixed-oxide sorbents prepared by the complexation technique were tested for high-temperature removal of H2S in the presence of hydrogen gas. Sorption experiments carried out at 627 T in a fixed-bed reactor showed higher reactivity and also higher sulfur retention capacity (over 0.15 g of S/g of sorbent) for the Mn-Cu mixed oxide than for the Mn-Cu-V mixed oxide. Successive sulfidation-regeneration cycles demonstrated that the MnCu mixed oxide was also more stable than Mn-Cu-V, maintaining its activity and about 90% of its sulfur retention capacity at the end of five cycles. Although formation of some MnSO4 was observed during regeneration at 700 T with a gas mixture containing 6% oxygen in nitrogen, this did not cause significant reduction in the activity of this mixed-oxide sorbent. It was also shown that a previously proposed deactivation model gave good predictions of the experimental breakthrough curves obtained with these sorbents

Dynamic analysis of removal and selective oxidation of H2S to elemental sulfur over Cu-V and Cu-V-Mo mixed oxides in a fixed bed reactor

Selective oxidation of H2S to elemental sulfur was studied using the Cu-V and Cu-V-Mo mixed oxide catalysts with different O-2/H2S ratios between 0 and 3. High activities and high sulfur selectivities reaching 0.98 were obtained with the Cu-V catalyst. The Cu-V-Mo mixed oxide catalyst showed higher activity with a somewhat less selectivity. The Cu-V catalyst, which was originally in the form of alpha-Cu2V2O7, was converted to Cu3VS4, CuS and VOx during the initial stages of reaction. Oxidized form of the catalyst resulted in the formation of mostly SO2. Partially reduced catalyst containing V+2 and V+4 was highly selective for the production of elemental sulfur, which was produced by a series of redox reactions involving lattice oxygen

Kinetics of H2S sorbtion on manganese oxide and Mn-Fe-Cu mixed oxide prepared by the Complexation Technique

Hydrogen sulfide sorption activities of manganese oxide and Mn-Fe-Cu mixed oxide sorbents were examined in a fixed bed reactor. Sulfur retention capacity of Mn-O sorbent was found to be quite high at 600 degrees C both in the absence and presence of hydrogen gas (0.17 and 0.14 g S/g sorbent, respectively). This sorbent has a high porosity and a relatively high surface area. Best regeneration temperature of this sorbent was found as 700 degrees C, with a gas stream containing 6% oxygen in nitrogen. Mn-Fe-Cu mixed oxide sorbent had a lower sulfur retention capacity (0.07 g S/g sorbent). However, both of these sorbents gave quite high initial sorption rate constants, resulting very sharp breakthrough curves. Deactivation model was shown to give good agreement with the experimental H2S breakthrough curves