CuO-CeO2/ZSM-5 composites for reactive adsorption of hydrogen sulphide at high temperature

Cu/TiO2 adsorbents modified by air plasma for adsorption-oxidation of H2S

In this study, non-thermal plasma (NTP) was employed to modify the Cu/TiO2 adsorbent to efficiently purify H2S in low-temperature and micro-oxygen environments. The effects of Cu loading amounts and atmospheres of NTP treatment on the adsorption-oxidation performance of the adsorbents were investigated. The NTP modification successfully boosted the H2S removal capacity to varying degrees, and the optimized adsorbent treated by air plasma (Cu/TiO2-Air) attained the best H2S breakthrough capacity of 113.29 mg H2S/gadsorbent, which was almost 5 times higher than that of the adsorbent without NTP modification. Further studies demonstrated that the superior performance of Cu/TiO2-Air was attributed to increased mesoporous volume, more exposure of active sites (CuO) and functional groups (amino groups and hydroxyl groups), enhanced Ti-O-Cu interaction, and the favorable ratio of active oxygen species. Additionally, the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated the main reason for the deactivation was the consumption of the active components (CuO) and the agglomeration of reaction products (CuS and SO42-) occupying the active sites on the surface and the inner pores of the adsorbents.

Two Birds with One Stone: Copper-Based Adsorbents Used for Photocatalytic Oxidation of Hg0 (Gas) after Removal of PH3

Cu_X/TiO₂ adsorbents with CuO as the active component were prepared via a simple impregnation method for efficient purification of phosphine (PH₃) under the conditions of low temperatures (90 °C) and low oxygen concentration (1%). The PH₃ breakthrough capacity of optimal adsorbent (Cu₃₀/TiO₂) is 136.2 mg(PH₃)·g_sorbent^-1, and the excellent dephosphorization performance is mainly attributed to its abundant sur face-active oxygen and alkaline sites, large specific surface area, and strong interaction between CuO and the support TiO₂. Surprisingly, CuO is converted to Cu₃P after the dephosphorization by Cu_X/TiO₂. Since Cu₃P is a P-type semiconductor with high added value, the deactivated adsorbent (Cu₃P/TiO₂) is an efficient heterostructure photocatalyst for photocatalytic removal of Hg⁰ (gas) with the Hg⁰ removal performance of 92.64% under visible light. This study provides a feasible strategy for the efficient removal and resource conversion of PH₃ under low-temperature conditions and the alleviation of the environmental risk of secondary pollution.

Kinetic Study on High-Temperature H2S Removal over Mn-Based Regenerable Sorbent Using Deactivation Model

The kinetics of high-temperature H₂S removal over Mn/Al sorbents prepared by co-precipitation method was investigated in a fixed-bed reactor using a deactivation model. The initial sorption rate constant (k ₀), deactivation rate constant (k _d), apparent activation energy (E _a), and deactivation energy (E _d) were obtained. The k ₀ and k _d values of Mn/Al sorbents are much higher than those of pure Mn₂O₃. This indicates that Mn/Al sorbents have higher reactivity on the removal of H₂S and less diffusion resistance caused by the formation of the sulfided product. The E _a and E _d values for the sorbent with the Mn content (wt %) of 35.4% are 38.18 and 31.05 kJ/mol, respectively. The deactivation model gives excellent predictions for the H₂S breakthrough curves in the sulfidation-regeneration process.

Cu/HZSM-5 Sorbent Treated by NH3 Plasma for Low-Temperature Simultaneous Adsorption-Oxidation of H2S and PH3

In this study, an NH₃ plasma-treated Cu/HZSM-5 sorbent was introduced to simultaneously remove H₂S and PH₃ in low-temperature and low-oxygen environments. The effects of the Cu loading amounts, modification methods, and plasma-treatment conditions on the adsorption-oxidation performance of the sorbents were investigated. From the performance test results, the sorbent treated by NH₃ plasma with the specific energy input (SEI, electrical input energy to the unit volume of gas) value of 1 J·mL^-1 (Cu/HZSM-5-[S1]) was identified as having the highest breakthrough capacities of 108.9 mg S·g^-1 and 150.9 mg P·g^-1 among all of the materials tested. After three times of regeneration, the sorbent can still maintain the ideal performance. The results of Fourier transform infrared (FT-IR) spectroscopy and CO₂ temperature-programmed desorption (CO₂-TPD) indicated that the NH₃ plasma treatment can introduce amino groups (functional groups) onto the sorbent surface, which greatly increases the number and strength of the basic sites on the sorbent surface. Results of N₂ adsorption/desorption isotherms and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) showed that the morphology of the sorbent changed after the plasma treatment, which exposed more active sites (copper species). In situ IR spectra showed that the amino groups are continuously consumed during the reaction process, indicating that these amino groups can help sorbents to capture gas molecules. Moreover, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses indicated that CuO is the main active species and the consumption of CuO and accumulation of the reaction products on the surface and inner pores of the sorbent are the primary reasons for the deactivation of the sorbent.

Removal of Hydrogen Sulfide with Metal Oxides in Packed Bed Reactors—A Review from a Modeling Perspective with Practical Implications

Sulfur, and in particular, H 2 S removal is of significant importance in gas cleaning processes in different applications, including biogas production and biomass gasification. H 2 S removal with metal oxides is one of the most viable alternatives to achieve deep desulfurization. This process is usually conducted in a packed bed configuration in order to provide a high solid surface area in contact with the gas stream per unit of volume. The operating temperature of the process could be as low as room temperature, which is the case in biogas production plants or as high as 900 ∘ C suitable for gasification processes. Depending on the operating temperature and the cleaning requirement, different metal oxides can be used including oxides of Ca, Fe, Cu, Mn and Zn. In this review, the criteria for the design and scale-up of a packed bed units are reviewed and simple relations allowing for quick assessment of process designs and experimental data are presented. Furthermore, modeling methods for the numerical simulation of a packed bed adsorber are discussed.