{"id":160305,"date":"2025-03-26T07:20:00","date_gmt":"2025-03-26T06:20:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=160305"},"modified":"2025-03-19T11:26:34","modified_gmt":"2025-03-19T10:26:34","slug":"benchmarking-selective-capture-of-trace-co2-from-c2h2-using-an-amine-functionalized-adsorbent","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/benchmarking-selective-capture-of-trace-co2-from-c2h2-using-an-amine-functionalized-adsorbent\/","title":{"rendered":"Benchmarking selective capture of trace CO2\u00a0from C2H2 using an amine-functionalized adsorbent"},"content":{"rendered":"\n\n\n

Purifying C2<\/sub>H2<\/sub>\u00a0by removing trace CO2<\/sub>\u00a0is critically needed yet challenged by their analogous physical properties. Herein, we report a commercial resin adsorbent HP20 (Diaion\u00ae HP-20 Resin) loaded with polyethyleneimine (PEI@HP20) which selectively captures trace CO2<\/sub>\u00a0and excludes C2<\/sub>H2<\/sub>. PEI@HP20 possesses a high CO2<\/sub>\u00a0adsorption capacity (4.35\u2009mmol\/g) at 100\u2009kPa and 298\u2009K and a record CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0uptake ratio compared with all reported CO2<\/sub>-selective adsorbents. The ideal adsorbed solution theory selectivity reaches 1.33\u00d7107<\/sup>. The pilot-scale pressure-temperature swing adsorption on 2\u2009kg PEI@HP20 further validated that it can obtain >99.99% purity C2<\/sub>H2<\/sub>\u00a0from CO2<\/sub>\/C2<\/sub>H2<\/sub>(1\/99, v\/v) mixtures with a high yield of 344.7\u2009g per cycle. The combination of multinuclear solid-state Nuclear Magnetic Resonance, Fourier Transform infrared spectroscopy and density functional theory calculations reveal that the performance of PEI@HP20 relies on a dual chemisorption\/physisorption mechanism. This work highlights a promising method to develop green, low cost, high efficiency, and readily scalable CO2<\/sub>-selective adsorbent.<\/p>\n\n\n\n

Introduction<\/h3>\n\n\n\n

Acetylene (C2<\/sub>H2<\/sub>) serves as one of the most essential industrial feedstocks and fuel, which is widely used in the petrochemical industry and metalworking processes1<\/a><\/sup>. In recent years, the market value of C2<\/sub>H2<\/sub>\u00a0has steadily increased by more than 5% every year, and is expected to reach around $14 billion by 20272<\/a><\/sup>. C2<\/sub>H2<\/sub>\u00a0is mainly derived from the partial combustion of methane, steam cracking of hydrocarbons, and the calcium carbide process. However, trace CO2<\/sub>(ca. <3%) is inevitably generated as a by-product during these procedures, which reduces the purity of C2<\/sub>H2<\/sub>\u00a0and may significantly hinder downstream applications3<\/a>,4<\/a><\/sup>. <\/p>\n\n\n\n

For example, the purity of C2<\/sub>H2<\/sub>\u00a0used in atomic absorption spectroscopy usually needs to reach 99.6% and in the semiconductor industry, carbon containing components made from C2<\/sub>H2<\/sub>, such as photolithographic masks and dielectric films have more stringent requirements for the purity of C2<\/sub>H2<\/sub>, which is up to 99.99 %5<\/a>,6<\/a>,7<\/a><\/sup>. Therefore, it is essential to remove the CO2<\/sub>\u00a0impurity to obtain high grade C2<\/sub>H2<\/sub>\u00a0(\u2009>\u200999.6%)8<\/a>,9<\/a><\/sup>. <\/p>\n\n\n\n

Currently, the prevalent conventional separation technologies to get high-purity C2<\/sub>H2<\/sub>\u00a0include solvent extraction and chemical absorption, which both suffer from heavy energy penalties and high operating costs while also generating environmental pollution issues (Fig.\u00a01<\/a>)10<\/a>,11<\/a><\/sup>. Thus, it is necessary to develop alternative separation technologies involving energy-efficient and environmentally benign processes to address these problems.<\/p>\n\n\n

\n
\"figure<\/a>
Fig. 1: Schematic diagram of CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0separation model.<\/figcaption><\/figure><\/div>\n\n\n

Adsorption separation based on porous materials has been envisaged for decades as a promising alternative separation technology with the possibility for high efficiency, low energy, and lower environmental impact compared to traditional separation methods (Fig.\u00a01<\/a>)12<\/a>,13<\/a>,14<\/a>,15<\/a>,16<\/a><\/sup>. However, similar physical properties such as molecular dimensions (C2<\/sub>H2<\/sub>: 3.3 \u00d7 3.3 \u00d7 5.7 \u00c53<\/sup>; CO2<\/sub>: 3.2 \u00d7 3.3 \u00d7 5.4 \u00c53<\/sup>), boiling points (C2<\/sub>H2<\/sub>: 189.3\u2009K; CO2<\/sub>: 194.7\u2009K), and the strict upper compression of C2<\/sub>H2<\/sub>\u00a0(2\u2009bar) make the efficient separation of trace CO2<\/sub>\u00a0from CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0mixtures a challenging task17<\/a><\/sup>. <\/p>\n\n\n\n

Painstaking efforts have been dedicated to utilize porous adsorbents such as zeolites, carbon molecular sieves, Metal-Organic Frameworks (MOFs), and Hydrogen Organic Frameworks (HOFs) for separation of CO2<\/sub>\/C2<\/sub>H2<\/sub>mixtures18<\/a>,19<\/a>,20<\/a><\/sup>. Current adsorbents are generally classified into C2<\/sub>H2<\/sub>-selective adsorbents and CO2<\/sub>-selective adsorbents based on their different binding preferences21<\/a><\/sup>. Since CO2<\/sub>\u00a0is the contaminant, CO2<\/sub>-selective adsorbents are desirable for purification of C2<\/sub>H2<\/sub>, which can directly isolate C2<\/sub>H2<\/sub>\u00a0products to avoid the energy-intensive desorption process. About 40% of energy consumption can be saved compared to C2<\/sub>H2<\/sub>-selective adsorbents12<\/a>,22<\/a><\/sup>. <\/p>\n\n\n\n

However, the majority of porous adsorbents typically exhibit preferential adsorption of the relatively acidic and polarizable C2<\/sub>H2<\/sub>\u00a0by hydrogen bonding and \u03c0-complexation23<\/a>,24<\/a><\/sup>. CO2<\/sub>-selective adsorbents thus are more rare and a universal methodology of designing such adsorbent is as of yet, non-obvious. Multiple strategies, such as complementary electrostatic interactions within compact pore spaces25<\/a><\/sup>, blocking strong binding sites of C2<\/sub>H2<\/sub>26<\/a><\/sup>,<\/sub>\u00a0and the use of predesigned pore shapes27<\/a><\/sup>\u00a0have been used to prepare CO2<\/sub>-selective adsorbents.<\/p>\n\n\n\n

However, these reported CO2<\/sub>-selective adsorbents, typically fall short due to insufficient ability to capture trace CO2<\/sub>\u00a0and sensitivity to water inhibition. They are also unsuitable for industrial application at large-scale due to the high cost of synthesis and lack of mature molding technology. Therefore, it is urgent to develop a common strategy for constructing effective trace CO2<\/sub>-selective adsorbents with the potential of direct industrialization.<\/p>\n\n\n\n

Here, we propose a facile synthetic strategy for CO2<\/sub>-selective adsorbents by immobilizing stable branched polyethyleneimine (PEI-800) into the commercially available porous resin HP20, which shows good preferential adsorption of trace CO2<\/sub>\u00a0over C2<\/sub>H2<\/sub>\u00a0through a dual chemisorption\/physisorption mechanism (Fig.\u00a01<\/a>). <\/p>\n\n\n\n

Such an adsorbent combines the advantages from both chemical adsorption and physical adsorption, leading to a green, efficient, and energy saving separation process. Initial attempts involved modifying the pore volume and environment of the moderately C2<\/sub>H2<\/sub>-selective HP20 by gradually varying the loading of PEI-800 to achieve inverse CO2<\/sub>-selective adsorption, and the resultant adsorbent displayed booming CO2<\/sub>\u00a0sorption and suppressed C2<\/sub>H2<\/sub>\u00a0sorption. <\/p>\n\n\n\n

Among those samples, the HP20 loaded with 50\u2009wt.% PEI-800 (referred to as PEI@HP20) displays the highest CO2<\/sub>\u00a0adsorption capacity (4.35\u2009mmol\/g at 100\u2009kPa, 2.88\u2009mmol\/g at 1\u2009kPa) among all the currently reported CO2<\/sub>-selective adsorbents and shows a new benchmark selectivity (up to 1.33\u2009\u00d7\u2009107<\/sup>) and a record-breaking uptake ratio of CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0(22.5), exhibiting unprecedented performance for CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0separation. <\/p>\n\n\n\n

Dynamic breakthrough experiments and pilot-scale pressure-temperature swing adsorption (PTSA) on 2\u2009kg PEI@HP20 further validated the ability to obtain high purity C2<\/sub>H2<\/sub>\u00a0(99.99%) from the CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0(1\/99, v\/v) mixtures at both dry and 100% relative humidity. The in situ adsorption-desorption cyclic experiments over 100 cycles show that performance remained near-consistent, particularly after the first 13 cycles. <\/p>\n\n\n\n

The combination of gas sorption analysis, in situ multinuclear Solid State Nuclear Magnetic Resonance (SSNMR) and density functional theory (DFT) calculations, reveals the exceptional performance of PEI@HP20 in CO2<\/sub>\/C2<\/sub>H2<\/sub>\u00a0separation lies in the formation of a reversible ammonium carbamate network inside HP20, followed by a simultaneous hydrogen-bond binding CO2<\/sub>\u00a0from the NH of ammonium carbamate. <\/p>\n\n\n\n

Additionally, the loading of amines greatly reduces HP20 porosity, suppressing the adsorption of C2<\/sub>H2<\/sub>. Thus, this work breaks the trade-off between adsorption capacity, selectivity, and cycling stability, and provides a general operable method for the construction of CO2<\/sub>-selective adsorbents. Moreover, the facile and inexpensive scale-up preparation strategy of the PEI@HP20 indicates it can be rapidly transferred into industrial production on demand.<\/p>\n\n\n\n

Results<\/h3>\n\n\n\n
<\/div>\n\n\n\n

Preparation and characterization of PEI@HP20<\/h3>\n\n\n\n

HP20, used herein, forms as a ball-shaped porous copolymer generated from polymerization of styrene and divinylbenzene28<\/a><\/sup>. The porosity of HP20 was determined by N2<\/sub>\u00a0gas isotherms at 77\u2009K, from which a Brunauer-Emmett-Teller (BET) surface area of 772 m2<\/sup>\/g and an average pore size of 8.5\u2009nm was derived (Supplementary fig.\u00a01<\/a>). HP20 was found by TGA to be thermally stable up to 400\u2009\u00b0C (Supplementary fig.\u00a02a<\/a>). <\/p>\n\n\n\n

PEI-800 is a commercially available macromolecular polyethyleneimine thermally stable up to 280 \u00b0C (Supplementary fig.\u00a02a<\/a>), with average molecular mass of 800\u2009g\/mol and molecular dynamics diameter of 16.2\u2009\u00c5 freely allowed into HP20 (Supplementary fig.\u00a02b<\/a>). PEI@HP20 was obtained by wet impregnation loading a specified amount of PEI-800 into commercially available HP20 particles in pure water (Fig.\u00a02a<\/a>\u00a0and Supplementary fig.\u00a03<\/a>). <\/p>\n\n\n\n

The optimized PEI@HP20 with the highest CO2<\/sub>uptake contained 50\u2009wt.% of PEI-800 (Supplementary fig.\u00a04<\/a>). Thus, subsequent PEI@HP20 mentioned herein refers to the sample obtained under this condition. The chemical composition and structure of HP20 before and after PEI-800 impregnation were first characterized by Fourier Transform infrared (FT-IR) spectroscopy (Fig.\u00a02b<\/a>). For pristine HP20, the broad band centered at 3422\u2009cm\u22121<\/sup>\u00a0is attributed to the O-H stretching of adsorbed water29<\/a><\/sup>. The three bands at 3020\u2009cm\u22121<\/sup>, 2926\u2009cm\u22121<\/sup>, and 2876\u2009cm\u22121<\/sup>\u00a0are assigned to the aliphatic and aromatic C-H stretching vibrations in the polystyrene resin, and the peaks at 1603\u2009cm\u22121<\/sup>, 1487\u2009cm\u22121<\/sup>, and 1447\u2009cm\u22121<\/sup>\u00a0are also due to the aromatic frame30<\/a>,31<\/a><\/sup>. <\/p>\n\n\n\n

Compared with HP20, some different bands in FT-IR spectra were exhibited in the sorbent after PEI-800 modification. The center of the broad peak was shifted from 3422\u2009cm\u22121<\/sup>\u00a0to 3366\u2009cm\u22121<\/sup>, corresponding to the N-H stretching vibrations of PEI-800 molecules32<\/a><\/sup>. The two broad peaks at 2926\u2009cm\u22121<\/sup>\u00a0and 2851\u2009cm\u22121<\/sup>\u00a0were attributed to -CH2<\/sub>– stretching vibrations in the PEI-800 molecules33<\/a><\/sup>. Additionally, the peaks appearing at 1315\u2009cm\u22121<\/sup>\u00a0and 1416\u2009cm\u22121<\/sup>\u00a0were associated with the N-COO\u2212<\/sup>stretching vibration of the carbamate species produced between amine groups and CO2<\/sub>\u00a0from air34<\/a>,35<\/a><\/sup>.<\/p>\n\n\n

\n
\"figure<\/a>
Fig. 2: Structure and multinuclear SSNMR spectra of PEI@HP20.<\/figcaption><\/figure><\/div>\n\n\n
<\/div>\n\n\n\n

You may read the complete article at https:\/\/www.nature.com\/articles\/s41467-025-57972-7<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Purifying C2H2\u00a0by removing trace CO2\u00a0is critically needed yet challenged by their analogous physical properties. Herein, we report a commercial resin adsorbent HP20 (Diaion\u00ae HP-20 Resin) loaded with polyethyleneimine (PEI@HP20) which selectively captures trace CO2\u00a0and excludes C2H2. PEI@HP20 possesses a high CO2\u00a0adsorption capacity (4.35\u2009mmol\/g) at 100\u2009kPa and 298\u2009K and a record CO2\/C2H2\u00a0uptake ratio compared with all […]<\/p>\n","protected":false},"author":59,"featured_media":160317,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"New PEI@HP20 adsorbent captures trace carbon dioxide from acetylene, enhancing industrial purification standards","footnotes":""},"categories":[5571],"tags":[25946,25947,10744,10416,10743],"supplier":[20610,25948,15621,2139],"class_list":["post-160305","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-co2-based","tag-acetylene","tag-adsorbent","tag-carboncapture","tag-circulareconomy","tag-useco2","supplier-china-university-of-petroleum","supplier-lanzhou-university","supplier-university-of-limerick","supplier-university-of-western-ontario"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/160305","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=160305"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/160305\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/160317"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=160305"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=160305"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=160305"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=160305"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}