Catalytic Hydrolysis Of Carbonyl Sulfide Research Articles

Boosting catalytic hydrolysis of carbonyl sulfide over K+ modified CeO2 nanospheres at low-temperature

Carbonyl sulfide (COS) as one of typical atmospheric sulfur-containing pollutants widely emitted from various industrial processes, which has a significant impact on human health and environmental safety. Currently, developing highly efficient catalysts to eliminate COS is of great significance for both fundamental catalytic research and actual industrial application. Here we report a series of K+ doping spherical cerium oxide (CeO2-S) that showing promote activity for catalytic hydrolysis of COS. The research results demonstrated that the K+-doped CeO2-S formed more Ce3+ and oxygen vacancies than CeO2-S. The hydrolysis activity and stability of CeO2-S for COS were significantly improved by the introduction of K+. Among them, the 0.2 K/CeO2-S showed the optimal performance. Further in-situ DRIFTS results revealed that a slight increase in alkalinity could enhanced the activation of H2O over 0.2 K/CeO2-S, and the generated surface active hydroxyl groups reacted with adsorbed COS to produce the intermediate species (HSCO2-), leading to the formation of H2S and CO2. The catalysts prepared in this paper exhibited promoted activity with low-temperature and high stability for COS hydrolysis, which is beneficial for practical industrial scale-up applications and provides novel insights into designing efficacious catalysts with efficient low-temperature activity and superior stability for removing COS.

Rational design of poisoning-resistant catalyst based on γ-Al2O3 for hydrolysis of carbonyl sulfide

Catalytic hydrolysis of carbonyl sulfide (COS) is an efficient way of desulfurization for industrial flue gas, while the frequently used Al2O3-based catalysts always suffer from sulfur poisoning leading to poor stability, especially in the presence of O2. With this regard, an analysis of the reaction pathway has been conducted, and the tri-coordinated Al in γ-Al2O3 is identified as the responsible site for poisoning, on which produced H2S is over-oxidized resulting in active sites covering. Density functional theory (DFT) has been adopted for dopant screening to eliminate tri-coordinated Al on γ-Al2O3, inhibit H2S over-oxidation, and prevent sulfur poisoning. Results show La, Fe, Ni, and Cu all can eliminate tri-coordinated Al, while only La-doped γ-Al2O3 exhibits inhibition to H2S oxidation, thus, improving activity and stability for γ-Al2O3. Experiments show COS conversion of 99 % over 30 h can be attained in the presence of O2, which agrees well with the DFT calculation.

Catalytic hydrolysis of carbonyl sulfide in blast furnace gas over Sm-Ce-Ox@ZrO2 catalyst.

Carbonyl sulfur (COS) is a prominent organic sulfur pollutant commonly found in the by-product gas generated by the steel industry. A series of Sm-doped CeOx@ZrO2 catalysts were prepared for the hydrolysis catalytic removal of COS. The results showed that the addition of Sm resulted in the most significant enhancement of hydrolysis catalytic activity. The 3% Sm2O3-Ce-Ox@ZrO2 catalyst exhibited the highest activity, achieving a hydrolysis catalytic efficiency of 100% and H2S selectivity of 100% within the temperature range of 90-180 °C. The inclusion of Sm had the effect of reducing the acidity of the catalyst while increasing weak basic sites, which facilitated the adsorption and activation of COS molecules at low temperatures. Appropriate doping of Sm proved beneficial in converting active surface chemisorbed oxygen into lattice oxygen, thereby decreasing the oxidation of intermediate products and maintaining the stability of the hydrolysis reaction.

Catalytic hydrolysis of carbonyl sulfide over Ce-Ox@ZrO2 catalyst at low temperature

Catalytic hydrolysis of carbonyl sulfide over Ce-Ox@ZrO2 catalyst at low temperature

Preparation of NiGa2O4 nanoflower for boosting catalytic hydrolysis of carbonyl sulfide

A nanoflower-like NiGa2O4 spinel was designed for the catalytic hydrolysis of COS. The COS hydrolysis activity of the NiGa2O4 nanoflower was significantly improved as compared to the Fe5Ga3O12 and CoGa2O4, which was ascribed to the enhanced diffusion and surface alkalinity. In the reaction, COS adsorption was significantly strengthened on the basic sites, and thereby the formation of intermediates such as HCO3– and HSCO2- was facilitated. The NiGa2O4 catalyst also demonstrated excellent sulfur tolerance and stability in long-term testing for COS hydrolysis using simulated industrial gas at 100 °C, maintaining ∼100% of H2S selectivity in the first 70 h.

Holey carbon nanomeshes with atomically Cu–N4 active sites for efficient carbonyl sulfide catalytic hydrolysis

Efficient catalytic hydrolysis of carbonyl sulfide (COS) into easy-to-handle products is crucial for mitigating energy and environmental issues. However, currently investigated catalysts are face the inherent problems of irreversible sulfation and carbonization during the catalytic reaction, making them limit in industrial application. Herein, we report a simple and practical method to synthesize isolated Cu–N4 site on holey nitrogen-modified carbon nanomeshes that can intensely resist sulfur poisoning with a good performance in COS hydrolysis. The representative Cu–N4/NC achieves a COS elimination of nearly 100% and a turnover frequency (TOF(Cu)) of 12.9 h−1 at 70 °C. Importantly, Cu–N4/NC exhibits high long-term stability, with no obvious decline of hydrolysis activity in the run of 32 h, outperforming most of the reported catalysts. The isolated Cu center can effectively modulate the adsorption and desorption of sulfur intermediates and thus avoid the sulfur poisoning of catalysts owing to its unique geometric structure and electronic properties. The in situ characterization demonstrates that isolated Cu–N4 site can effectively catalyze the COS hydrolysis via the adsorbed *HSCO2 and *H intermediates. Our discovery provides an opportunity to design highly active and durability COS desulfurization catalysts with potential for industrial application.

Research on the Catalytic Hydrolysis of COS by Fe−Cu/AC Catalyst and Its Inactivation Mechanism at Low Temperature**

AbstractFor removing carbonyl sulfide (COS) from industrial waste gas at low temperatures, the critical approach is to prepare an efficient and cheap catalyst. In this paper, Fe/Cu modified coal‐based activated carbon (AC) was prepared by co‐precipitation method and tested for the catalytic hydrolysis of carbonyl sulfide (COS) at low temperatures in a fixed‐bed reactor. The results showed that the best mole ratio of Fe/Cu was 1 : 1 and the best content of metal oxides was 50 %. BET, XRD, XPS, FTIR, and SEM investigated the structure and surface properties. COS was hydrolyzed on Fe2O3 to produce H2S and CO2, and H2S reacted with CuO to have CuS. At the same time, H2S reacted with Fe2O3 to produce FeS and elementary sulfur. Oxidized elemental sulfur was to form sulfuric acid, which responded with Fe2O3 to form sulfates. The sulfates would be deposited on the catalysts’ surface and block the pore structure. Deactivation of metal oxides and blockage of pore structures were the main reason for catalyst deactivation.

The catalytic mechanism of intercalated chlorine anions as active basic sites in MgAl-layered double hydroxide for carbonyl sulfide hydrolysis.

In order to make clear the role of intercalated anions in layered double hydroxides (LDHs) for catalytic hydrolysis of carbonyl sulfide (COS), the adsorption and reaction characteristics of COS over the simple Mg2Al-Cl-LDH model catalyst were studied by both theoretical and experimental methods. Density functional theory (DFT) calculations by CASTEP found that the chloride ions in LDH function as the key Brønsted base sites to activate the adsorbed H2O with enlarged bond length and angle, facilitate the dissociative adsorption of intermediates including mono-thiocarbonic acid (MTA) and hydrogen thiocarbonic acid (HTA), and participate in the formation of transient states and subsequent hydrogen transfer process with decreased energy barriers during COS hydrolysis. COS hydrolysis will preferentially go through the dissociated intermediates of mono-thiocarbonates (MT) and hydrogen thiocarbonates (HT) with dramatically decreased energy barriers, and the rate-determining step of COS hydrolysis over Mg2Al-Cl-LDH will be the nucleophilic addition of C=O in COS by H2O (Ea = 1.10 eV). The experimental results further revealed that the apparent activation energy (0.89 eV) of COS hydrolysis over Mg2Al-Cl-LDH is close to theoretical value (1.10 eV), and the accumulated intermediates of MT, HT, or carbonate were also observed by FT-IR around 1363 cm-1 on the used Mg2Al-Cl-LDH, which are well in accordance with the theoretical prediction. The demonstrated participation of intercalated chlorine anions in the evolution of intermediates and transient states as Brønsted base sites during COS hydrolysis will give new insight into the basic sites in LDH materials.

Efficient catalytic removal of COS and H2S over graphitized 2D micro-meso-macroporous carbons endowed with ample nitrogen sites synthesized via mechanochemical carbonization

Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide (COS) and hydrogen sulfide (H2S) is of great significance in terms of industrial safety and environmental protection. We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900 °C. The as-synthesized graphitized catalysts, designated as 2D-NHPC-x (x = urea/glucose mass ratio), are endowed with an ultra-high concentration (12.9–20.2 wt%) of stable and versatile nitrogen sites (e.g. pyrrole and pyridine) which are anchored on the surface via stable covalent bonding. As a result, the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H2S, and the H2S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials. Among the prepared catalysts, 2D-NHPC-x can catalytically hydrolysize 91% of COS to H2S at 30 °C, whereas the conversion ratio over the common catalysts g-C3N4 and Fe2O3 are below 6.0%. Furthermore, these catalysts also exhibit H2S conversion and sulfur selectivity of nearly 100% at 180 °C with long-time durability, which is higher than those of the most reported carbon-based catalysts. In contrast, the H2S capacities of activated carbon, ordered mesoporous carbons (OMC) and N-doped OMC are 3.9, 1.5 and 2.39 mmol g−1, respectively. Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H2S.

Surface characterization of metal oxides-supported activated carbon fiber catalysts for simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide

The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 60°C was tested. The effects of preparation conditions on the catalyst properties were investigated, including the kinds and amount of metal oxides and calcination temperatures. The activity tests indicated that catalysts with 5 wt.% Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS2. The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), carbon dioxide-temperature programmed desorption (CO2-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR). And the metal cation defects were researched by electron paramagnetic resonance (EPR) method. The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores, then improved catalytic hydrolysis activity. The DRFTIR results revealed that -OH species could facilitate the hydrolysis of COS and CS2; -COO and -C–O species could facilitate the oxidation of catalytic hydrolysate H2S. And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS2 adsorption.

Experimental and Theoretical Studies on the Influence of Carrier Gas for COS Catalytic Hydrolysis over MgAlCe Composite Oxides.

Catalytic hydrolysis of carbonyl sulfide (COS) over metal frameworks derived MgAlCe composite oxides catalyst is investigated under N2 and CO atmosphere. A combination of experimental and theoretical methods, including in situ IR, X-ray photoelectron spectroscopy, and density functional theory calculations, is used to explain the difference of catalytic activity. Research results indicate that M–OH groups play the most important role in COS hydrolysis, but the distribution of the M–OH groups is affected by CO. There is no competitive adsorption effect between N2 and COS on the surface of catalyst but CO and COS. Meanwhile, the hydrolysis reaction of COS is an instantaneous reaction and a noninstantaneous reaction under N2 and CO atmosphere, respectively. In general, under N2 atmosphere, COS is directly adsorbed on the surface of the catalyst and most of the −OH groups are adsorbed as M–OH formation. Under CO atmosphere, most of the active sites occur as CO due to the competitive adsorption effect.

Metalated carbon nitrides as base catalysts for efficient catalytic hydrolysis of carbonyl sulfide

A new type of base catalyst was designed and prepared by metalation of carbon nitrides with alkali metal ions. The as-prepared metalated carbon nitride composites showed enhanced basicity and efficient catalytic hydrolysis of carbonyl sulfide. The results of this study demonstrate that the metalation of carbon nitrides holds great promise for base catalysis applications.

Mechanistic and kinetic study on the catalytic hydrolysis of COS in small clusters of sulfuric acid

The catalytic hydrolysis of carbonyl sulfide (COS) and the effect of small clusters of H2O and H2SO4 have been studied by theoretical calculations. The addition of H2SO4 could increase the enthalpy change (ΔH<0) and decrease relative energy of products (relative energy<0), resulting in hydrolysis reaction changed from an endothermic reaction to an exothermic reaction. Further, H2SO4 decreases the energy barrier by 5.25 kcal/mol, and it enhances the catalytic hydrolysis through the hydrogen transfer effect. The (COS + H2SO4-H2O) reaction has the lowest energy barrier of 29.97 kcal/mol. Although an excess addition of H2O and H2SO4 increases the energy barrier, decreases the catalytic hydrolysis, which is consistent with experimental observations. The order of the energy barriers for the three reactions from low to high are as follows: COS + H2SO4-H2O < COS + H2O + H2SO4-H2O < COS + H2O+(H2SO4)2. Kinetic simulations show that the addition of H2SO4 can increase the reaction rate constants. Consequently, adding an appropriate amount of sulfuric acid promotes the catalytic hydrolysis of COS both kinetically and thermodynamically.

Tuning the growth of Cu-MOFs for efficient catalytic hydrolysis of carbonyl sulfide

Development of the high activity, promoter-free catalysts for carbonyl sulfide (COS) hydrolysis is important for the efficient utilization of various feedstocks. In this study, the Cu-based metal-organic framework HKUST-1 is synthesized by a simple and mild anodic-dissolution electrochemical method. The physical and chemical properties of the samples are characterized by several techniques, including scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis and X-ray photoelectron spectroscopy. The results reveal that the synthesis voltage plays a crucial role in controlling the morphology of the resulting HKUST-1. The obtained samples function as novel catalysts for the hydrolysis of COS. A high efficiency, approaching 100%, can be achieved for the conversion of COS at 150 °C over the optimal HKUST-1 synthesized at 25 V. This is significantly higher than that of the sample prepared by the traditional hydrothermal method. Additionally, the effects of the water temperature and the flow velocity on the hydrolysis of COS are also investigated in detail. Finally, a possible reaction pathway of COS hydrolysis over HKUST-1 is also proposed. This work represents the first example of MOFs applied to the catalytic hydrolysis of COS. The results presented in this study can be anticipated to give a feasible impetus to design novel catalysts for removing the sulfur-containing compounds.

Influence of the preparation conditions of MgAlCe catalysts on the catalytic hydrolysis of carbonyl sulfide at low temperature

The catalytic hydrolysis of carbonyl sulfide (COS) at 50 °C over Mg–Al–Ce mixed oxides derived from hydrotalcite-like compounds was studied.

Energy Utilization of Yellow Phosphorus Tail Gas: Simultaneous Catalytic Hydrolysis of Carbonyl Sulfide and Carbon Disulfide at Low Temperature

AbstractThe CO in yellow phosphorus tail gas can be used as energy source in the one‐carbon chemical industry, but the harmful gases carbonyl sulfide (COS) and carbon disulfide (CS2) are in co‐existence with CO and so must be removed. Modified microwave coal‐based activated carbon (Fe/MCAC) loaded with different metal oxides was manufactured by a sol–gel process, and used for the simultaneous catalytic hydrolysis of COS and CS2 at low temperature (30–70 °C). The influences of Cu–Ni doping and reaction conditions on catalytic hydrolysis reaction were investigated. The results showed that the optimum addition agents are copper and nickel, and the best mole ratio of Fe/Cu/Ni was 10:2:0.5. The X‐ray diffractometry results show that the doping agent could control the generation of sulfate, which can suppress the hydrolysis activity of the catalysts. Further characterization revealed that larger specific surface areas and pore volumes are favorable and enhance the catalytic hydrolysis activities. The products of simultaneous catalytic hydrolysis (S/SO42− species) could block the pore structure and surface active sites, which leads to a decline of the catalytic hydrolysis activity. Excessively high reaction temperatures (&gt;50 °C) could enhance the catalytic hydrolysis of COS but inhibit catalytic hydrolysis of CS2. Excessively high relative humidity (RH) and O2 content could lead to formation of more sulfates, and decrease the catalytic efficiencies towards simultaneous hydrolysis of COS and CS2.

ChemInform Abstract: The Hydrolysis of Carbonyl Sulfide at Low Temperature: A Review

AbstractReview: 80 refs.

Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over Al2O3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon (CAC) catalysts loaded by Al2O3 were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 30–70 °C. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2 concentration, gas hourly space velocity (GHSV) and relative humidity (RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3 calcined at 300 °C had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 °C, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of O2 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.

Simultaneous catalytic hydrolysis of low concentration of carbonyl sulfide and carbon disulfide by impregnated microwave activated carbon at low temperatures

The blank microwave coal-based activated carbons (MCAC) and blank microwave coconut shell activated carbons (MCSAC) were tested for simultaneous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperature (at 50°C). MCAC and MCSAC loaded by Fe–Cu–Ni metal mixed oxides were prepared by sol–gel method, and also tested for the simultaneous catalytic hydrolysis process. The results showed that Fe–Cu–Ni/MCSAC catalyst had the superior activity for the simultaneous catalytic hydrolysis of COS and CS2. These modified catalysts were characterized by XRD, BET, EDS and XPS, the results of which can help us to understand the reasons of the superior catalytic activity and the reasons of catalyst deactivation. Lower generation of sulfate (K3Na(SO4)2), high specific surface areas and more pore sizes of 0.3–1.2nm and 3.5–4.0nm may be the important role in COS and CS2 catalytic hydrolysis reaction. The XPS results showed that most of products on the exhausted catalysts were S/SO42- species which accumulated on the active carbon’s surface and had a negative effect on the hydrolysis activity, and the contents of S/SO42- species of exhausted Fe–Cu–Ni/MCAC were higher than which of exhausted Fe–Cu–Ni/MCSAC catalysts.

Low temperature hydrolysis of carbonyl sulfide using Zn–Al hydrotalcite-derived catalysts

A series of Zn–Al hydrotalcite-like compounds (HTLCs) were synthesized by co-precipitation method. The mixed oxides derived from HTLCs were tested for the catalytic hydrolysis of carbonyl sulfide (COS) at relatively low temperatures of 50°C. These catalysts were characterized by X-ray diffraction (XRD) and Thermogravimetry/Derivative Thermogravimetry Analysis (TG-DTA) and the results can help us to understand the effect of preparation conditions. The results showed that the Zn–Al hydrotalcite-like compounds were efficient precursor in preparing active and stable catalysts for hydrolysis of COS. The catalyst performance was strongly related to the synthesis pH and calcination temperature. The optimum condition was pH of 10, and calcination temperature of 400°C. Although water was indispensable for hydrolysis of COS, the excess water would hinder the adsorption of COS. In general, COS was hydrolyzed to H2S, which is depending on the chemistry of the derived oxides. The end-products of hydrolysis were simple substance S and sulfate. The presence of oxygen will accelerate the formation of the final product.