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CO2 hydrogenation to methanol is attracting specific interest because of its potential economic and environmental benefits in transforming waste CO2 to value-added hydrocarbons. Copper-based catalysts are documented as efficient and widely applied, whereas insufficient catalytic properties of conventional catalysts hinder their application. Herein, catalysts using Mg-Al hydrotalcite (HT) as the carrier of Cu/ZnO/ZrO2 (CZZ) nanoparticles were prepared to exploit special advantages of hydrotalcite on copper dispersion and catalytic performance. The results show that CZZ nanoparticles can be uniformly dispersed on external surfaces of HT, elevating BET surface areas of CZZ-HT samples by at least 2.5 times compared to pure CZZ. The HT carrier also enriches strong basic sites and hence elevates CO2 adsorption capabilities in the range of reaction temperature. Both copper surface area and copper dispersion of CZZ-HT samples are improved dramatically. A catalyst containing 45.1 wt% of CZZ shows 1.1 times higher copper surface area per gram CZZ and 1.6 times higher copper dispersion than the reference CZZ. Subsequent reactions demonstrate the CZZ-HT samples show remarkably promoted turnover frequency (TOF) for methanol synthesis and retain considerable catalyst stability. The typical catalyst prepared in this research, at the reaction temperature of 523 K and pressure of 3.0 MPa, presents a 68.2% higher methanol STYCu per gram copper and an 117.0% higher SMeOH/SCO ratio than the commercial catalyst. The support HT plays a crucial role for the enhanced catalytic performance physically and chemically. Thus, the as-prepared CZZ-HT catalyst provides a significant improvement for CO2 utilization.

Adsorption materials play a key role in determining the efficiency of the pressure swing adsorption process. The selectivity of CO2 over CH4 on most zeolite adsorbents drops dramatically with incre...

In this study, a novel green strategy through fusion hydrothermal method was adopted for in-situ synthesis of chabazite. The morphological and physiochemical characteristic of the prepared adsorbent was determined by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. The characterization results revealed that prepared chabazite posses fine particles (2–5 µm) and porous structure which could be employed for capture of CO2 molecules. In order to gain an understanding of the adsorption performance of prepared adsorbent, different types of adsorption isotherms and kinetic adsorption models were studied. The results indicated that synthesized adsorbent has shown significant high CO2 adsorption capacity as well as CO2/N2 selectivity. As compare to pseudo-first-order, pseudo-second-order and Elovich model, the kinetics data of CO2 adsorption on chabazite fitted well with the Bangham model. This strategy may be a novel approach for large-scale synthesis of chabazite that exhibits excellent adsorption performance for industrial CO2 capture.

CO2 hydrogenation to methanol plays an increasingly important role in fields of chemical engineering, energy generation and H2/CO2 utilization, and the prohibitive costs result partially from the high operating pressures required for practical application. Thus, a hybrid catalyst/adsorbent consisting of Cu-ZnO-ZrO2 supported on hydrotalcite (named CZZ@HT) was synthesized, characterized and analyzed in this study with the intent that the adsorbent hydrotalcite would enhance the local concentration of CO2 and assist in catalyst dispersion. The as-prepared CZZ@HT catalyst containing 43.4 wt% of CuO-ZnO-ZrO2 in the form of well dispersed nanoparticles possessed a considerable BET surface area and external surface area after reduction. A remarkable copper dispersion of 58.7% was thereby achieved. This reduced catalyst displayed elevated uptakes of H2O and CO2 at 473 K compared to the reference adsorbent-free catalyst and presented enhanced adsorption capacities of CO2 at reaction temperatures due to collective effects of physisorption and chemisorption. Catalysis experiments on a fixed bed reactor using the rCZZ@HT catalyst showed a methanol selectivity of 83.4% and a SMeOH/SCO ratio of 5.0 in products. A control experiment in which hydrotalcite was replaced with quartz (named rCZZ&QS) showed considerably lower conversion at low pressure and demonstrated the enhancing effect of the hydrotalcite support. The new catalyst could achieve the same methanol productivity as the control catalyst at 2.45 MPa lower reaction pressure. This lower pressure corresponds to a ∼61.3% savings in energy consumption for compression. Accordingly, the CZZ@HT is a promising candidate for CO2 hydrogenation to methanol at moderate pressures.

Electrical swing adsorption (ESA) is an interesting cyclic adsorption technology which relies on rapid Joule heating of the adsorbent to liberate adsorbed molecules such as CO2. In this study we used a novel hybrid zeolite/activated carbon honeycomb to implement ESA and compared it to conventional vacuum swing adsorption (VSA) for CO2 capture. We then combined electrical and vacuum swing adsorption (VESA) to assess the merits of this dual regeneration technology for recovering CO2 from a 15% CO2/N2 gas stream at low pressure. With a simple VSA-only cycle, a CO2 downstream purity of only 17–23% was achievable when the desorption pressures varied from 30 to 10 kPa. This was primarily due to the adsorbent’s poor adsorption characteristics which provided little change in CO2 adsorption capacity over this pressure range. A CO2 product purity of 15–34% and a recovery of 29–78% was achieved with ESA as the electrification time was extended from 30 s to 180 s. The combined VESA process provided a CO2 purity of 33% and recovery of 72% with a short electrification time of 30 s at a mild desorption pressure of 10 kPa. Energy calculations indicate that the total specific energy for VESA was lower than ESA alone but still higher than VSA, although the latter suffered from low purity.

There is an increasing global attention toward hydrogen as a green energy carrier, primarily because of the environmental concerns associated with global warming issues. It is expected that the produced hydrogen from various sources may be injected to the natural gas grid for economical transportation and use. One interesting option is to evaluate technologies for extracting the hydrogen from the natural gas pipeline for applications using high purity hydrogen. However, natural gas is a complex mixture including CH4, C2H6, CO2, N2 and trace amounts of C3-C6 hydrocarbons. This function requires a natural gas/hydrogen separation technology which must not only operate with low capital and energy cost, but must also provide hydrogen of sufficient purity. The goal of current work therefore was to take a mixture of hydrogen/natural gas of representative concentrations and produce high purity hydrogen using a bespoke pressure swing adsorption (PSA) cycle. A six-bed PSA system with 12 steps was developed and simulated in Aspen Adsorption software to this end. A three-layered adsorption column was designed to capture different groups of components of the mixture selectively within each layer. Informed by measured and literature equilibrium isotherm data, silica gel was chosen as the pre-layer to remove heavy hydrocarbon components and most of the CO2; activated carbon in the main-layer to mainly adsorb methane, and LiLSX zeolite in the top-layer to remove trace nitrogen which had eluted from the earlier layers, for obtaining pure hydrogen product. High purity hydrogen product (>99%) with high recovery (>85%) was achieved with the PSA system for different hydrogen concentrations (5–30%) in the 30 bar feed stream. We also compared the PSA system against an electrolyzer generating hydrogen onsite. Our analysis suggests that the PSA competes favorably, even at a low hydrogen recovery of 40% in cases where the PSA plant is built at a pressure reduction station.

The structure of ZSM-25, a RHO family zeolite, was resolved recently. Recent reports focused on Na-ZSM-25 as a promising CO2 adsorbent with high CO2 working capacity and exceptional CO2/CH4 ideal s...

Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol. The active sites of the Cu based catalyst were discussed. The performance and structural development of the catalyst were observed during CO2 hydrogenation. A mechanism for the deactivation of the catalyst was discussed. The key factors that affect the deactivation of the catalyst were found. Cu nanowire sample was characterized by SEM, EDS, XRD, and BET. The results show that Cu nanowires have very high sintering resistance and catalytic stability. This helps to develop high performance catalysts. The changes in the grain size, SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur. Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels. The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst. However, the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.

Electrical Swing Adsorption is a version of temperature swing adsorption in which the adsorbent is regenerated by Joule heating. To accomplish this feature, the adsorbent must be a continuous, electrically conducting member, which usually restricts the application to activated carbon samples. Unfortunately, the CO2 adsorption capacity and selectivity of activated carbon is not as good as silica-alumina materials such as zeolites. In addition, the low resistance of activated carbon samples often means that the dominant heat generation occurs at the contact resistance between the electrodes and the sample, depriving the bulk sample of temperature increase. Use of the silica-alumina materials though, is prevented by its electrically insulating properties. In the current work, we present a novel approach to solve this dilemma. We have synthesized a novel hybrid activated carbon (from phenolic resin) and zeolite NaUSY monolith with attractive electrical and adsorption properties. The adsorption capacity of CO2 on the novel adsorbent was more than twice that of an AC-only material prepared from phenolic resin. The electrical resistance increased from 4.59 × 10−4 Ω m for activated carbon to 1.18 × 10−2 Ω m for the hybrid adsorbent so that energy loss in the contacting surfaces between the adsorbent surface and copper electrode was reduced significantly from 73% of the total resistance to 18%. This novel hybrid adsorbent has excellent potential in ESA applications.

We reported a new polymorphous core-shell metal-organic framework (MOF) in the form of a three-dimensional MOF core wrapped in a two-dimensional layered MOF shell by applying a general acid-solvent synergy synthesis. This hybrid material can achieve high adsorptive selectivity/capacity simultaneously, which is validated by the unary isotherms of CO

CO2 hydrogenation, in which CO2 conversion to methanol plays a key role, is of increasing importance in mitigating the climate crisis. However, high reaction pressures are required to conduct methanol synthesis because of poor catalytic performance of conventional catalysts, leading to high energy consumption. In this study, a novel strategy was applied to promote methanol synthesis by adsorption-enhanced CO2 hydrogenation. Catalysts made from Cu-ZnO-Al2O3 mixed with different hydrotalcite contents (named CZA-HT) were prepared by physically mixing a commercial copper-based catalyst for methanol synthesis with hydrotalcite for high temperature CO2 adsorption. In these catalysts, only the commercial copper-based component contains the active part for CO2 hydrogenation and its copper surface area is 48.1 m2 g−1 with an optimal reaction temperature of 523 K. Hydrotalcite exhibits no catalytic activity, yet the catalytic performance of the CZA-HT catalysts were clearly facilitated by CO2 adsorption on HT. The sample containing 40 wt% hydrotalcite and 60 wt% CZA showed the highest methanol selectivity of 73.4% and a methanol yield of 4.4% among all samples. The reaction was conducted at a low reaction pressure of 30 bar (much lower than conventional pressure), so that the methanol yield was not high. However, it is observed that the methanol formation rate based on a unit mass of active CZA always increases as the hydrotalcite content in CZA-HT increases, confirming the promotion effects of CO2 adsorption on HT on catalytic performance. The mechanism of adsorption enhanced catalytic reaction was also analysed and discussed, in which the well mixed finer particles of CZA and HT perform better than CZA alone with a 73.9% higher methanol yield.

The potential of novel polyethyleneimine (PEI) based sorbent and process designs to safeguard the stability of the PEI type sorbent stability for CO2 post combustion capture (PCC) via vacuum swing adsorption (VSA) application was investigated. In-situ thermogravimetric analysis (TGA) combined with CO2 partial pressure swing adsorption (PPSA) processing, Fourier Transform Infrared (FTIR) spectroscopy and lab scale VSA processing of adsorber columns were employed for this purpose. The inventions were found to inhibit the dehydration of ammonium carbamates into ureas, and, thereby, better maintain the integrity of the sorbent and its CO2 working capacity under key process conditions.

Performance of four adsorbents (three zeolites and one molecular sieve carbon) for CO2–CH4 separation from simulated biogas feed containing 42% CO2 (balance methane) is compared in a simple four step dual bed vacuum swing adsorption (VSA) cycle. The VSA cycle consisted of four sequential steps in each column namely adsorption, cocurrent depressurization, evacuation and pressure equalization. Among the adsorbents tested, zeolite NaUSY appears to give the best results for producing pipeline grade methane (>98%) at recoveries exceeding 85%. The methane productivity obtained by the present process is in the range of 11–16 mol/h/kg, which is considerably higher than the literature reported values with zeolite and carbon based adsorbents. The high methane productivity of the present process is due to the absence of purge step during regeneration with methane rich adsorption product as well as due to absence of any blow down step in the VSA cycle. Another advantage of the present process is that operation for bi...

The influence of water vapor on the adsorption of CO2 in carbon capture by vacuum swing adsorption (VSA) was described. VSA experiments with single and multilayered columns using alumina and zeolite 13X were conducted to understand the migration of water. The penetration depth of water in the column could be controlled by maintaining the purge-to-feed ratio above a critical value. At high water content in the feed (>4%), employment of a water adsorbing prelayer was essential to prevent failure of the carbon capture process. A simple axial working capacity model predicts the penetration depth of water in the column for a given feed temperature and adsorption isotherm, and the layering ratio can be selected accordingly. Although water is detrimental to CO2 capture with polar adsorbents, long-term recovery of CO2 is still possible by appropriate layering and ensuring an adequate purge-to-feed ratio. © 2013 American Institute of Chemical Engineers AIChE J 60: 673–689, 2014

The capture of CO2 with adsorption processes is greatly complicated by the presence of high water levels in most process and flue gas streams. One option is to use activated carbon of appropriate hydrophobicity. The interaction of water and CO2 on carbon materials in VSA processes is therefore of great interest and it is this feature which the current study addresses. The adsorption equilibrium isotherms of H2O, CO2 and N2 on activated carbon (coconut shell Acticarb GC1200) were measured over the range 25–60 °C and 0–1 bar. The Type V isotherm exhibited by water required a non-Langmuir type representation. In this case, Rutherford’s extended CMMS model was employed to describe water adsorption. Breakthrough experiments as well as one bed vacuum swing adsorption studies were undertaken to investigate the impact of water on CO2 adsorption and its eventual impact on a separation process. Simulations were also conducted to help interpret the data. Our analysis showed that there was little effect of CO2 and water on each other’s adsorption on the carbon material beyond the dilution effect on partial pressure of each component. The single bed vacuum swing experiment showed almost identical recovery and purity of CO2 in the presence of water as in the dry case. However, the presence of water required additional pumping energy and led to an increase in CO2 capture energy of about 35%. There is a need to improve carbon materials to further exclude water without substantially decreasing CO2 capacity and selectivity.

Structured adsorbents with attractive characteristics have been developed for use in CO2 capture applications. 5A zeolite monolithic structures with a hierarchical designed channel/pore system and high zeolite content approaching 92 wt% were prepared. The body of the monoliths contained three different sizes of channels and pores; macro, meso and micro. The developed monoliths showed outstanding performance on CO2 separation from CO2/N2 gas mixtures compared to commercial 5A beads. The equilibrium isotherms of pure gas adsorption were collected, CO2/N2 binary gas breakthrough experiments were conducted, and pressure drop along beds packed with the monoliths or 5A beads was measured. The experimental data were simulated and the results showed that effective diffusivity was six times higher and pressure drop was 1.3 times lower for 5A monolith bed compared to 5A beads bed. The high effective diffusivity, low pressure drop and comparable adsorption capacity of the prepared 5A monoliths indicate that they are ideal candidates for rapid pressure swing adsorption applications.

In order to solve the water issues when 13X zeolite was applied to capture CO2 from wet flue gas by vacuum swing adsorption process, multi-layered adsorption system was considered regarding activated alumina F200 and silica gel based Sorbead WS as pre-layer materials. LBET (extended Largmuir-BET) model and extended CMMS (cooperative multimolecular sorption) equation were simulated respectively to describe water loading on F200 and Sorbead WS. The two equations can be well added into our in-house simulator to simulate double-layered CO2-VSA (vacuum swing adsorption) process. Results indicated that water can be successfully stopped in pre-layers with a good CO2 capture performance.

Activated carbon is well applied in pressure swing adsorption process for CO 2 capture. The real flue gas contains saturated water vapor as well. In this study, single and binary components adsorption equilibrium and kinetics of H 2O/CO 2 were studied according to their adsorption isotherms and breakthrough curves. Results showed that activated carbon could adsorb high amount of CO 2 and low amount of N 2, that showed a good CO 2/N 2 selectivity. As activated carbon contains the functional groups, the activated carbon can adsorb large amount water at high water partial pressure. However, because of different CO 2 adsorption mechanism, water adsorption has almost no impact on CO 2 adsorption on activated carbon. The kinetics study showed that CO 2 adsorption velocity on activated carbon is much faster than that of H 2O.

ETS-4 and ETS-10 titanosilicates were prepared from fly ash and anatase, as silica and titanium sources respectively, via a hydrothermal procedure for the first time. The fusion of fly ash by alkali was carried out at a relatively low temperature and the use potassium fluoride salt was avoided in the synthesis of ETS. The by-product of this process is mainly NaCl, which is a useful source material for industry. The energy efficiency and yield of the synthesis process was improved by directly recycling the final filtrate after recovering the product viz ETS-4. All the ETS materials were characterized in terms of structural morphology, thermal stability and surface/pore properties. The properties of ETS-4 prepared from fly ash by the filtrate recycling method were comparable to that from commercial sources. The results show that ETS type materials can be prepared from cheaper resources, with good purity, comparable physico-chemical properties as well as excellent adsorption properties with lower environmental impact.

Due to the high absolute humidity of real flue gas, activated carbon, a hydrophobic adsorbent, was used to selectively adsorb CO2 by vacuum swing adsorption in this study. The objective of this work is to study the feasibility and advantage of CO2 capture along with simultaneous moisture removal by activated carbon and the effect of H2O on CO2 capture from wet flue gas streams. Through experiment and analysis, the “S” shape isotherms of water indicated water was easier to be desorbed from activated carbon. Then a cone shape model was proposed to depict water distribution inside the adsorption bed. As a consequence, water vapor hardly influenced the CO2 capture performance. Moreover, the process can be operated under a relatively high vacuum pressure and short evacuation time. The preliminary results showed that our one-bed VSA process could yield a good CO2 recovery of over 80% and a reasonable purity of 43%.

Zeolite A and A + X mixtures were prepared from coal-fly ash procured from China by using an alkali fusion method. X-ray diffraction showed that both the materials were crystalline and reproducible. Scanning Microscopy revealed that pure zeolite A particles have cubic morphology while the mixture shows intergrowth of cubic and pyramidal crystals. The surface area for A + X mixture was around 330 m2/g which is higher than zeolite A, however, lower than typical X zeolite. CO2 and N2 adsorption isotherms were measured and the data was fitted by the Dual Site Langmuir equation. These zeolites were then tested for CO2 capture at different temperatures in a process with a nine step cycle. When compared with 13X zeolites at higher temperature (∼90 °C), both the zeolite A + X mixture and zeolite A prepared from fly ash showed better performance in CO2 capture from flue gas because they have higher selectivity of CO2 over N2.

Gas storage in a safe and economical way is an important aspect of modern life. This study reports on the behavior of the zeolite potassium chabazite (Si/Al = 2.2) as a nanocontainer to store N2 and CH4 by a “temperature” controlled nanovalve. We reveal the effect of extra-framework cation type and density on the adsorption characteristics by measuring a series of isotherms. Temperature programmed desorption (TPD) experiments are conducted to identify the working temperature for gas storage. The results show a N2 storage capacity of 3.02 mmol/g if loaded above 266 K and 5 MPa and held below 223 K and at atmospheric pressure. For CH4 storage, a more mild working temperature (i.e., above 279 K) is observed due to its larger molecular size than that of N2. Chabazite is a promising gas storage container because its features can be tailored to encapsulate a series of gases of different size by tuning its extra-framework cation type and density.

The development of structured adsorbents with attractive characteristics is an important step in the improvement of adsorption-based gas-separation processes. The improved features of structured adsorbents include lower energy consumption, higher throughput, and superior recovery and purity of product because of the even flow distribution, very low mass-transfer resistance, and low pressure drop in combination with a reasonable adsorption capacity. This study examines the vacuum-swing adsorption (VSA) CO2 separation performance of structured adsorbents in the form of thin NaX films grown on the walls of ceramic cordierite monoliths, and the results are compared with NaX pellets. Adsorption equilibrium and dynamic properties are explored experimentally. The CO2 breakthrough front for the NaX film grown on the 400 cells/in.2 (cpsi) monolith was close to ideal and indicated that axial dispersion was very small and that the mass-transfer resistance in the film was very low. The breakthrough front for the stru...

All flue gases contain water vapour along with carbon dioxide, nitrogen, etc. Vacuum Swing Adsorption (VSA), which has been successfully studied for post-combustion dry CO2 capture in our group, is strongly affected by the overwhelming competitive adsorption of water vapour on CO2 adsorbents. In this study, breakthrough experiments have been conducted to measure the single/binary adsorption isotherm data of CO2 and water vapour on zeolite 13X and a proprietary alumina-based adsorbent alumina CDX to study the competitive adsorption effect on each other. The CO2 adsorption data are well represented by the Dual site Langmuir isotherm equation. Based on the above understanding, a single column multilayered VSA unit was used with a guard-bed layer of superior desiccant and a main layer of 13X to simultaneously remove water (3–4% by volume) and capture CO2 (10–12%) at 30 ∘C within the same process. In this study, activated alumina CDX was selected as the appropriate pre-layer. Furthermore, we have investigated the effects of operating parameters on the multilayered CO2/H2O VSA performance. The water front was accurately located in the bed and the interaction of CO2 and water vapour indicates a clear indication of a water loaded zone and a CO2 loaded zone. The result demonstrates that water front has been successfully held in the pre-layer and CO2 product purity of 76.9% and purity of 67% were achieved for the double layered single column CO2/H2O VSA.

We report an unusual operating regime for a chabazite zeolite in which the adsorption selectivity for N2 over CH4 inverts from being more selective for N2 at 253 K, to becoming less selective with increasing temperature and eventually becoming selective for CH4 over N2 above 293 K.

© The Royal Society of Chemistry. Eight-membered ring (8 MR) zeolites hold large potential for industrial CO2 separations such as biogas separation. They offer large selectivity due to the constrained environment for adsorption, especially when large cations are present in the interconnecting windows. The Rb- and Cs-exchanged ZK-5 zeolites (8 MR KFI type zeolites) were studied for kinetic CO2/CH4 separation. First, Rb-ZK-5 and Cs-ZK-5 were thoroughly characterized via chemical analysis, argon porosimetry, X-ray diffraction and Rietveld refinements. Afterwards, the CO2/CH4 separation potential of both adsorbents was assessed via the measurement of kinetic and equilibrium data (T = 261.15 - 323 K), breakthrough measurements at 303 K (P = 1 - 8 bar), and simulations of their performance. The high occupation of the central 8 MR sites with large cations causes strong diffusional limitations for CH4 on Rb-ZK-5 and Cs-ZK-5. As a result, both zeolites effectively separate CH4 from CO2 with very high selectivities (α = 17 at 1 bar and 303 K). Despite their very large CO2 selectivities, the performance of Rb-ZK-5 and Cs-ZK-5 was still lower than for the benchmark 13X zeolite on a larger scale. Future research needs to further unravel the adsorption mechanism on low-silica 8 MR zeolites and their corresponding potential in separation processes such as biogas purification. This journal is crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available after a 12 month embargo period history: Received 15 October 2014; Accepted 3 November 2014; Accepted Manuscript published 3 November 2014; Version of Record published 20 November 2014 ispartof: Rsc Advances vol:4 issue:107 pages:62511-62524 status: published

Catalysts based on Cu/CuO–ZnO supported on mesoporous carbon (FDU-15) were synthesised and tested for methanol production from CO2 and H2. The catalytic activity was strongly dependent on the method by which the Cu and Zn components were loaded onto the carbon support. Three synthetic methods were trialled and the materials produced were characterised by various techniques. The materials with better contact between the Cu/CuO and ZnO particles were catalytically more active towards methanol production (CZC-3 > CZC-2 > CZC-1). The methanol production rate for CZC-3 (7.3 mmol g–1 h–1) was higher, on a catalyst weight basis, than that of a commercial catalyst (5.6 mmol g–1 h–1). Also, CZC-3 had a higher turnover frequency (1.8 × 10–2 s–1) than the commercial catalyst (0.2 × 10–2 s–1). This work demonstrates that Cu/CuO and ZnO particles supported on mesoporous carbon, prepared by an appropriate method, are promising catalysts for methanol synthesis from carbon dioxide.

Capture of CO2 from high temperature process streams, such as those arising in the Integrated Gasification Combined Cycle (IGCC) process, is receiving increasing attention. In this paper, we report the performance of zeolite 13X for CO2 capture from IGCC streams at elevated temperatures. Isotherms of CO2 adsorption on zeolite 13X at 90 °C, 120 °C, and 200 °C were measured and the fitted parameters were used for cyclic adsorption process design. Four different cycles were designed and tested with gas mixtures representing syngas compositions from a coal gasification pilot plant. These four cycles were then applied to CO2 separation from real coal gasification syngas. The experiments carried out with real syngas showed that zeolite 13X can be used for CO2 capture with acceptable performance even with impurities present in the syngas.

The separation capability of carbon dioxide from high temperature syngas was evaluated using zeolite 13X, calcium chabazite and hydrotalcite materials by means of measuring isotherms and breakthrough curves under the different operating temperatures at 7 bar and assessing the performance in pressure vacuum swing adsorption (PVSA) cycles. Four different PVSA processes were designed for a dual-bed apparatus and operated at 120 °C and 200 °C. Zeolite 13X was selected for the PVSA processes due to its acceptable adsorption capacity for CO 2 at elevated temperatures and fast kinetics. CO 2 product purities ranging from 80 to 98% were obtained from a feed gas of 12% CO 2 . From the PVSA experiments, it was found that a pressure equalisation step and product purge step improved the carbon capture performance in terms of CO 2 concentration. Contamination of the adsorbents was observed after 24 hours of operation and the contaminants originating from the syngas were identified as heavy hydrocarbons.