Facile synthesis of PEI-GO@ZIF-8 hybrid material for CO2 capture

Pristine graphene oxide (GO) sheets were pretreated with polyethyleneimine (PEI) to prepare PEI-modified GO (PEI-GO), which was further inserted with ZIF-8 crystals to form a novel PEI-GO@ZIF-8 nanocomposite for CO₂ capture. The good dispersion of PEI and interlayer growth of ZIF-8 within the GO sheets is helpful for high CO₂ adsorption. Therefore, the PEI-GO@ZIF-8 nanocomposite show high surface area and enhanced CO₂ adsorption capacity. The adsorption capacity of the PEI-GO@ZIF-8 nanocomposite was six times higher than that of the pristine GO and ZIF-8. The CO₂/N₂ adsorption selectivity was significantly improved due to amine groups loading which provide more sites for CO₂ adsorption. The preferential adsorption of CO₂ over N₂ makes PEI-GO@ZIF-8 nanocomposite be a promising candidate in the field of CO₂ capture.     

Effect of base promoter on activity of MCM-41-supported nickel catalyst for hydrogen production via dry reforming of methane

Dry reforming of methane (DRM) is considered a promising reforming technology that converts natural gas in the Natuna Sea into synthesis gas, which can be further utilized to produce beneficial chemicals such as olefins, alcohols, and liquid hydrocarbons. However, the challenges in commercializing the DRM process are carbon deposition and sintering of the catalyst at high temperatures, because of which the catalyst is easily deactivated. This study aimed to test the activity and stability of MCM-41-based catalysts for the DRM; determine the effect of promoter type on the activity and stability of MCM-41-based catalysts; and determine the effect of base promoter addition on the amount of carbon deposition. MCM-41-based catalysts were synthesized using incipient wetness impregnation method. XRD, N₂ Physisorption, H₂-TPR, CO₂-TPD, and TGA analysis were conducted to determine the physicochemical properties of the catalysts. The catalysts activity was tested in a fixed-bed reactor, under atmospheric pressure at 700 °C. Overall, all catalysts exhibited good stability for 240 min. Moreover, catalysts with Mg and Ca promoters showed the highest CH₄ and CO₂ conversion among all catalysts. Ni–Mg/MCM-41 catalyst yielded 72% CH₄ conversion and 54% CO₂ conversion, meanwhile Ni–Ca/MCM-41 yielded 69% CH₄ conversion and 55% CO₂ conversion. Furthermore, MCM-41-based catalysts with base promoter produced small amount of carbon deposition.     

Carbon nanoflake hybrid for biohydrogen CO2 capture: Breakthrough adsorption test

Biohydrogen gas is a hot topic for H₂ fuel at present. However, removal of the unwanted CO₂ through adsorption is required before any system is supplied with high-purity H₂ gas. Herein, we prepared a novel carbon nanoflake hybrid for efficient biohydrogen CO₂ capture by combining the advantages of carbon, metal oxide, and amine. Among the samples, SH800 showed a remarkable high CO₂ adsorption capacity of 29.8 wt.% (6.77 mmol/g) at 25°C and 1 atm, the highest ever reported at low pressure and temperature. The regeneration experiment also demonstrated robust reversibility over five cycles in the absence of heat treatment. Moreover, it displayed a highly accessible adsorption site with a Brunauer-Emmett-Teller (BET) surface area of 600 m²/g and an optimal 6.6-nm average mesopore structure. Another hybrid named SH500 was also developed. This hybrid showed a comparable CO₂ uptake of 27.8 wt.%, being competitive to SH800 but with entirely different chemical properties. Both samples were analyzed by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy, (XPS) and were tested for CO₂ capture through a breakthrough experiment. A highly porous solid adsorbent was also produced via soft-template synthesis. In summary, the correct amount of dynamic factors, such as high surface area, mesopore-micropore morphology, activation temperature, metal hybridization, and N moieties, played a major role in the carbon engineering of CO₂ adsorbent.     

Sorption-enhanced ethanol steam reforming on Ce-Ni/MCM-41 with simultaneous CO2 adsorption over Na- and Zr- promoted CaO based sorbent

In this study, sorption-enhanced ethanol steam reforming (SEESR) is investigated using a Ce-Ni/MCM-41 as a catalyst in the presence of Na or/and Zr promoted CaO-based adsorbents. Ce-Ni/MCM-41 and promoted sorbents were synthesized by wet impregnation method. The catalyst was characterized by XRD, FTIR, TGA, EFSEM, TEM, H₂-TPR and N₂ adsorption/desorption and promoted sorbents were studied by XRD, EFSEM, BET, TEM and TGA analysis. Sorption experiments were performed to verify sorbent activity for CO₂ removing. The results indicated that with doping different promoter on CaO sorbent and also with increasing Na loading, there was an increase in BET surface area, the reduction in particle size and thereupon an enhancement in CO₂ sorption capacity. Higher BET surface area, smaller particle size, and superior CO₂ sorption capacity were obtained on Na-Zr-CaO sorbent. Sorption-enhanced steam reforming process of ethanol on synthesized catalyst and sorbents were performed at 600 °C and water to ethanol molar ratio of 6. The effect of sorbent to catalyst ratio and the arrangement of sorbent and catalyst (like two separated layers and the mixture of sorbent and catalyst in a single layer) were also studied. The best results were demonstrated on Na-Zr-CaO sorbent and with the separated array. Hydrogen production via a SEESR process with Na-Zr-CaO as sorbent was ∼94% that is 24% more than that of conventional ethanol steam reforming (ESR) reaction.     

Hydrogen production from CH4 dry reforming over Sc promoted Ni / MCM-41

The activity of Ni supported on MCM-41 catalyst with/without scandium promoter was investigated for hydrogen production. The performance of the catalysts with different Sc loadings (0.00, 0.10, 0.25, 0.50, 0.75, 1.00 and 3.00 wt%) was examined. N₂ adsorption-desorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of the catalytic materials. The prepared catalysts were tested in dry reforming of methane. The effect of Sc addition on activity, hydrogen yield, H₂/CO ratio and stability are discussed. CH₄ and CO₂ conversions were measured under atmospheric pressure at 800 °C. Low Sc loading (<0.75 wt%) showed a positive effect on H₂ yield, CH₄ and CO₂ conversions. Addition of Sc strengthened the interaction of Ni with support and also increased the basicity which in turn affected the amount of CO₂ adsorbed on the surface of the catalyst. Notably, promoting with Sc almost suppressed the carbon formation leading to outstanding catalytic stability; thus 17% carbon deposition reduction was attained. The effect of different reaction temperatures, GHSV and CH₄:CO₂ ratio was also investigated.     

High-purity hydrogen production by sorption-enhanced methanol steam reforming over a combination of Cu–Zn–CeO2–ZrO2/MCM-41 catalyst and (Li–Na–K) NO3·MgO adsorbent

In this study, sorption-enhanced methanol steam reforming (SEMSR) was applied to generate high-purity hydrogen. The mesoporous MCM-41 as support and CuO, ZnO, CeO₂, ZrO₂ as active agents and promoters were employed for the catalyst preparation. In addition, (Li–Na–K) NO₃·MgO as a CO₂ adsorbent was prepared by the wet mixing method. The fresh and used catalysts were characterized by XRD, BET, FTIR, FESEM, TEM, H₂-TPR and TGA analyses. Also, the CO₂ sorbent was studied by XRD, BET, FESEM, TEM and TGA analyses before and after the reaction. The SEMSR performances of the synthesized catalyst and adsorbent were evaluated experimentally in a fixed-bed reactor. The effect of various conditions such as temperature, WHSV, feed molar ratio and sorbent/catalyst ratio were investigated. The best results were obtained at 300 °C, a feed molar ratio (water/methanol) of 2:1, a WHSV of 1.62 h^?1, and the sorbent/catalyst ratio of 8:1, which produced 99.8% hydrogen, 25% more than the hydrogen production during conventional methanol steam reforming. Moreover, the cyclic stability of the catalyst and the sorbent was studied for 10 cycles.     

Green synthesis of MCM-41 derived from renewable biomass and construction of VOx-Modified nickel phyllosilicate catalyst for CO2 methanation

In order to achieve green synthesis of MCM-41 and address the sintering problem of Ni-based catalyst supported on silica material, MCM-41 with regular spherical morphology was prepared using sodium silicate extracted from renewable equisetum fluviatile as silicon source, and then a group of nickel phyllosilicates were synthesized via the reaction of MCM-41 sphere and nickel nitrate under hydrothermal condition. Much denser nanosheets corresponding to lamellar nickel phyllosilicate were formed on the surface of MCM-41 sphere with the raise of hydrothermal temperature in the range of 180–220 °C, resulting in the nickel content varying from 17.2 to 41.8 wt%. Fine Ni particles with size smaller than 6 nm could be obtained on the 750^oC-reduced catalyst owing to the strong nickel-silica interaction derived from Ni-phyllosilicate. After the addition of V₂O₅ promoter, Ni particle size was further reduced to around 4.5 nm at high Ni loading above 30 wt%. Vanadium species was in the mixed valence state of V(III), V(IV) and V(V) after reduction, which increased the electron cloud density of Ni⁰, resulting in high catalytic activity of the VO_x-modified Ni-phyllosilicate catalyst for CO₂ methanation. In a 100 h-400^oC-lifetime test and 600 °C-steam hydrothermal treatment, the VO_x-modified Ni-phyllosilicate catalyst also showed high long-term stability, excellent sintering resistance of metallic nickel particles and high hydrothermal stability due to the strong surface confinement effect of nickel phyllosilicate and promotion of VO_x species. In all, this work provided a green synthesis of MCM-41 as well as an efficient Ni/SiO₂ catalyst derived from nickel phyllosilicate for CO₂ methanation.     

Which is the better catalyst for CO2 methanation – Nanotubular or supported Ni-phyllosilicate?

In order to investigate effects of morphology and crystalline phase of different Ni-phyllosilicate catalysts on the catalytic performance for CO₂ methanation, nanotubular Ni-phyllosilicate and MCM-41 supported Ni-phyllosilicate were synthesized through hydrothermal reaction of sodium silicate or MCM-41 with nickel nitrate. On one hand, nanosheets attributing to 2:1 type nickel phyllosilicate (Ni₃Si₄O₁₀(OH)₂·5H₂O) were uniformly grown on the surface of MCM-41 spheres to form the MCM-41 supported Ni-phyllosilicate (Ni/M). On the other hand, 1:1 type Ni-phyllosilicate with nanotubular morphology (Ni/N) was synthesized through the reaction of Na₂SiO₃ and nickel nitrate. After a series of tests and characterizations, it was found that Ni/N exhibited low thermal stability and poor anti-sintering property, leading to poor catalytic activity for CO₂ methanation. On the contrary, Ni/M was very stable, which obtained unchanged morphology and fine Ni particles after 750^oC-reduction, resulting in high catalytic activity and long-term stability for CO₂ methanation. In all, morphology and crystalline phase of Ni-phyllosilicate obviously affected catalytic performance, and the supported Ni-phyllosilicate catalyst was much better than the nanotubular Ni-phyllosilicate for CO₂ methanation in this work.     

Surface and interface engineering in CO2-philic based UiO-66-NH2-PEI mixed matrix membranes via covalently bridging PVP for effective hydrogen purification

We report on the fabrication of the defect-free mixed-matrix membrane (MMM) based on the polyethylenimine (PEI) matrix with uniformly dispersed metal-organic framework (MOF) filler UiO-66-NH₂, covalently bonded by polyvinylpyrrolidone (PVP). The key feature of the molecular level-controlled filler deposition in prepared UiO-66-NH₂-PVP-PEI membranes was bridging the MOF particles to the PEI polymer matrix via PVP polymer chains. Such an approach improved the polymer-filler interface interactions and boosted the MOF dispersion into the polymer matrix for higher MOF loadings up to 23 wt %. The overall membrane structure and properties were characterized using FTIR, XRD, TG, DSC, SEM and 3D optical profiler techniques. Obtained results revealed the uniform dispersion of UiO-66-NH₂, the strong polymer-filler interface interactions and entanglement of PEI with UiO-66-NH₂-PVP. Furthermore, the outstanding CO₂/H₂ separation performance was determined for the UiO-66-NH₂-PVP-PEI membrane with 18 wt % of MOF loading; the average CO₂ permeability of 394 Barrer and the separation factor of 12 for circa 100 h of the membrane testing overcome the 2008 Robeson reverse upper bound limit. Such improved CO₂/H₂ separation performance was achieved due to the combination of the diffusion-solution mechanism with the preferential adsorption of the CO₂ via the reversible bicarbonate reaction with amino groups of the UiO-66-NH₂ and PEI which acts as fixed CO₂ carrier sites in MMM structure.     

Impregnated carbon–ionic liquid as innovative adsorbent for H2/CO2 separation from biohydrogen

Currently, purification is a considerably important technology for biohydrogen (bioH₂) production as a renewable energy resource. Adsorption methods are promising techniques for separation of CO₂ from the H₂/CO₂ mixture of bioH₂. In this study, the adsorbent is synthesized by impregnating activated carbon (AC) with ionic liquid (IL). The ILs were prepared using choline chloride and zinc chloride at different wt% with the AC, i.e., 0.5 wt%–3 wt%. The physical and chemical properties of the synthesized adsorbents, such as surface morphology, porosity, and structures, were investigated and characterized by using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller analysis (BET). To investigate the actual adsorption performances, the effects of different synthesized adsorbent types and feed gas flow rates, i.e., 0.1–1.0 L min⁻¹, were observed. Hence, a commercial gas composed of CO₂ and H₂ mixture with different compositions, i.e., 40, 50, and 60 vol%, was used as synthetic bioH₂ gas. The adsorption capacity of CO₂, i.e., adsorption capacity, were determined using single adsorber column (0.6 L) at a temperature of 300 K and pressure of 1 bar. Results showed that adsorption capacity decreased with the increased feed gas flow rate. Moreover, the carbon impregnated with 1 wt% of IL showed the most excellent adsorption capacity at 84.89 mg of CO₂/g of adsorbent. The present results are the initial findings generated for the bioH₂ separation technology for future high-purity hydrogen production.     

Developing cross-linked poly(ethylene oxide) membrane by the novel reaction system for H2 purification

In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H₂ purification and CO₂ capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state ¹³C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO₂ have been examined in detail. Interestingly, the investigation on CO₂ plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO₂ permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO₂ permeability continuously increases with the loading pressure. The gas transport results illustrate that CO₂ has much larger permeability than that of any tested gas (including H₂, N₂ and CH₄) attributing to the CO₂-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H₂ purification and CO₂ capture applications.     

Effects of synthesis methods on performance of CuZn/MCM-41 catalysts in methanol steam reforming

CuZn-based catalysts are active in production of hydrogen by methanol steam reforming. However, there is a need to have further insight on their physico-chemical properties to improve selectivity to hydrogen. Therefore, a series of CuZn/MCM-41 catalysts was synthesized by four different routes; one pot hydrothermal synthesis (OPMCM), co-impregnation (COMCM), serial impregnation (SRMCM) and copper impregnated on Zn-MCM-41 (ZNMCM). Samples of catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), inductively coupled plasma (ICP) emission spectrometry, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). XRD revealed disruption in the ordered pore network typical in MCM-41 for all catalysts synthesized and also showed that the one pot synthesis catalyst had wide spread dispersion of Cu and Zn. SEM micrographs captured irregularly shaped particles of different sizes. While XPS showed that different Cu and Zn species were formed within the catalyst matrix. XPS also confirmed that there was wide spread dispersion and interaction of Cu and Zn with MCM-41 matrix in the OPMCM catalyst. COMCM and OPMCM demonstrated the highest activity with 88 and 65% methanol conversion with corresponding H₂ selectivity of 91 and 86% respectively. They are better than SRMCM and ZNMCM which had average H₂ selectivity of 19% and 31% respectively. CO selectivity was less than 1.8% for the COMCM and OPMCM catalysts. While SRMCM and ZNMCM had CO selectivity's as high as 8.9% and 7.2% respectively. The data generated shows that catalytic activity is largely affected by the nature of Cu species within the catalyst matrix.     

Bifunctional Ni–CaO catalysts modified with CeO2 and inert Ca12Al14O33 for sorption-enhanced steam reforming of ethanol

In this work, sorption-enhanced steam reforming of ethanol (SE-SRE) process was studied using Ni–CaO-based bifunctional catalysts modified with Ca₁₂Al₁₄O₃₃ (mayenite) and CeO₂. The CaO and CaO/Ca₁₂Al₁₄O₃₃ sorbents were synthesized by a sol-gel method and, subsequently, CeO₂ and Ni were added by the incipient wetness impregnation method. These materials were characterized by BET surface area, thermogravimetric analysis (TGA), in situ X-ray diffraction (XRD), and in situ X-ray absorption near edge structuare (XANES). In addition, the catalysts were tested on 10 cycles of SE-SRE reaction and regeneration. In general, the characterization results revealed an inverse relationship between average crystallite size of CaO and CO₂ sorption capacity. By the in situ XRD/XANES, the addition of the mayenite reduced by half the average crystallite size of CaO and increased the interaction between support and active phase. As a consequence, the catalyst containing mayenite (NiCaAl) showed the best CO₂ capture uptake and stability, which could be justified mitigation of the CaO sintering effect by the inert material presence. Great stability was also observed in the catalytic tests, since the duration of the pre-breakthrough stage for NiCaAl and for the catalyst containing maynite and ceria (NiCaAlCe) remained constant over the reaction cycles. In terms of hydrogen production, NiCaAl catalyst showed the highest H₂ molar fraction during the pre- (90%) and post-breakthrough. The CeO₂ addition slightly favored the methane formation, although did not bring significant benefits in the CO₂ capture and catalytic performance. Therefore, NiCaAl showed the best CO₂ capture capacity and stability, which led to the best SE-SRE performance.     

Preparation of PPO-silica mixed matrix membranes by in-situ sol–gel method for H2/CO2 separation

Poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)-silica mixed matrix membranes (MMMs) were synthesized through the in-situ sol–gel method. The effects of the acid–base catalysis conditions and silica loading weight on the gas separation performance of the membranes were investigated. The functional groups, crystalline structure, thermal stability, and morphology of the MMMs were examined using Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA), respectively. The results indicate that using the in-situ sol–gel method to synthesize PPO-silica MMMs is beneficial for improving the adhesion between the silica and polymer and for the dispersion of the silica. The additives significantly enhanced the thermal stability of the membranes. Compared with pure PPO membranes, the PPO-silica MMMs prepared with 10 wt.% acid-silica loading exhibited the best H₂/CO₂ separation properties: H₂ permeability was enhanced from 82.1 to 548.7 Barrer, and an H₂/CO₂ separation ratio of approximately 3.56 was observed.     

Catalytic oxidative desulfurization of dibenzothiophene utilizing molybdenum and vanadium oxides supported on MCM-41

As a series of bimetallic nanocatalysts, molybdenum/vanadium oxides supported on the silica (MoO₃/V₂O₅/MCM-41) were prepared by the impregnation. Their catalytic activity in the oxidation of dibenzothiophene was investigated using H₂O₂ as an oxidant. Textures and surface properties of the prepared catalysts were characterized using FT-IR, XRD, FESEM-EDX and N₂ adsorption/desorption techniques. The effects of main process variables including H₂O₂/DBT molar ratio, catalyst dosage, reaction temperature and reaction time were analyzed by employing the response surface methodology (RSM). The effect of the MoO₃/V₂O₅ loading on the catalytic performance of the catalysts was also investigated. The results indicated that the catalytic activity of the catalyst was increased by enhancing the MoO₃/V₂O₅ content. Thus, the catalyst with high MoO₃/V₂O₅ loading (20%MoO₃/20%V₂O₅/60%MCM-41) indicated the highest catalytic activity and could convert 99.06% of dibenzothiophene under the optimum conditions. Mass and FT-IR analysis demonstrated that the major product of dibenzothiophene oxidation was its corresponding sulfone. The catalyst could be recycled five times without any considerable reduction in its catalytic activity. The kinetics of the reaction fitted the pseudo-first-order equation pretty well. Eventually, a reaction mechanism for the catalytic oxidation of DBT in the presence of MoO₃/V₂O₅/MCM-41 was proposed.     

Biomass pyrolysis-gasification over Zr promoted CaO-HZSM-5 catalysts for hydrogen and bio-oil co-production with CO2 capture

In order to enhance biomass conversion technology, a three-stage conversion process for biomass pyrolysis-gasification with applied Zr modified CaO-HZSM-5 catalysts is proposed for hydrogen and bio-oil co-production with CO₂ capture. The process is divided into three parts: biomass pyrolysis, steam biochar gasification, and catalyst regeneration with CO₂ capture. The Zr modified CaO-HZSM-5 catalysts are prepared using ion exchange and incipient wetness impregnation methods. The bifunctional catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), energy dispersive X-ray fluorescence (EDXRF), and transmission electron microscopy (TEM). The cycled CaO-Zr-ZSM-5 catalysts were also characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results indicate that CaO-HZSM-5 catalyst shows the best bio-oil selectivity (56% of phenols and 73% of aromatic compounds determined by GC/MS). Furthermore, higher hydrogen yields and concentration can be obtained using the modified CaO-Zr/H-ZSM-5 catalysts.     

Combined catalytic partial oxidation and CO2 reforming of methane over ZrO2-modified Ni/SiO2 catalysts using fluidized-bed reactor

Nickel on zirconium-modified silica was prepared and tested as a catalyst for reforming methane with CO₂ and O₂ in a fluidized-bed reactor. A conversion of CH₄ near thermodynamic equilibrium and low H₂/CO ratio (1<H₂/CO<2) were obtained without catalyst deactivation during 10 h, in a most energy efficient and safe manner. A weight loading of 5 wt% zirconium was found to be the optimum. The catalysts were characterized using X-ray diffraction (XRD), H₂-temperature reaction (H₂-TPR), CO₂-temperature desorption (CO₂-TPD) and transmission election microscope (TEM) techniques. Ni sintering was a major reason for the deactivation of pure Ni/SiO₂ catalysts, while Ni dispersed highly on a zirconium-promoted Ni/SiO₂ catalyst. The different kinds of surface Ni species formed on ZrO₂-promoted catalysts might be responsible for its high activity and good resistance to Ni sintering.     

Hydroxyl aluminium silicate clay for biohydrogen purification by pressure swing adsorption: Physical properties,adsorption isotherm,multicomponent breakthrough curve modelling,and cycle simulation

Hydroxyl aluminium silicate clay (HAS-Clay) is a novel adsorbent in pressure swing adsorption for CO₂ capture (CO₂-PSA) and can also adsorb H₂S. To investigate the performance of HAS-Clay as a CO₂-PSA adsorbent, multicomponent breakthrough curves were determined using experimental measurements and theoretical models, and, based on those results, CO₂-PSA simulations were conducted. The breakthrough curves produced from the theoretical models agreed well with those derived from experiment. CO₂-PSA with HAS-Clay could purify biomass-gasification-derived producer gas of contaminants (carbon dioxide, methane, carbon monoxide, and hydrogen sulfide) with high CO₂ recovery and low energy input. The CO₂ recovery rate of CO₂-PSA with HAS-Clay was 58.4%, and the CO₂ purity was 98.4%. The specific energy demand was 2.83 MJ/kg-CO₂. In addition, the H₂S regenerability of HAS-Clay was investigated. The results show that HAS-Clay retained the ability to adsorb H₂S at a steady-state value of 0.02 mol/kg for the regeneration cycles. Therefore, it is suggested that CO₂-PSA with HAS-Clay is suitable for CO₂ separation from multicomponent gas mixtures.     

Preparation and adsorption denitrogenation from model fuel or diesel oil of heteroatoms mesoporous molecular sieve Co-MCM-41

The MCM-41 and Co-MCM-41 molecular sieves were confirmed by characterization with XRD, FTIR, nitrogen adsorption, and NH₃-TPD. Denitrogenation of model fuel containing about 1,737.35 μg (nitrogen)/g or diesel oil was studied over the samples. The molecular size of quinoline, calculated by using density functional theory, was 7.116 × 5.002 Å, implying that it easy access to mesoscale pores of molecular sieves. The adsorption denitrogenation capacity of Co-MCM-41 was clearly more effective than MCM-41 due to its strong acidity and chemisorption. The basic nitrogen removal of diesel oil on MCM-41 or Co-MCM-41 was 68.22 and 65.91%, respectively.     

Study of hydrogen adsorption properties on MCM-41 mesoporous materials modified with nickel

MCM-41 samples were modified with different Ni loadings by wet impregnation method and characterized by XRD, ICP, EPMA-EDS, N₂ adsorption–desorption and hydrogen adsorption at 77 K at high and low pressure conditions. The hydrogen adsorption studies for the MCM-41 host and the impregnated samples showed that small amounts of Ni ions in MCM-41 improved the hydrogen storage capacity by spillover effect.