Amine-modified MCM-41 mesoporous silica for carbon dioxide capture
TL;DR: In this article, an amine functionalized material, MCM-41-NH2, exhibited a higher uptake of CO2 at very low pressures compared with the nongrafted material.
About: This article is published in Microporous and Mesoporous Materials.The article was published on 2011-08-01. It has received 295 citations till now. The article focuses on the topics: Mesoporous silica & Adsorption.
Citations
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TL;DR: In this paper, dry solid adsorbents are classified into non-carbonaceous (e.g., zeolites, silica, metal-organic frameworks and porous polymers, alkali metal, and metal oxide carbonates) and carbonaceous materials with a focus on recent research.
525 citations
TL;DR: In this paper, the most fundamental aspects of adsorptive CO2 separation are discussed in order to illuminate the "sweet spot" to be explored when electronic structure, polarity and pore size/geometry are rationally balanced and optimized.
Abstract: Fundamental aspects and actual developments of selective CO2 capture from relevant sources (flue gas or air) by reversible physisorption are critically reviewed. Thermodynamic as well as kinetic principles of CO2 adsorption in the presence of other gases are linked to current approaches of materials development. Whilst hundreds or even thousands of porous materials have been evaluated for CO2 capture, research in this field is still full of challenges, as for instance a feasible physical adsorbent for CO2 capture for direct capture from air has still not been found. Current attempts towards the optimization of materials in terms of CO2 uptake/selectivity, regenerability, tolerance against water, and cost most often exclude each other. The aim of this article is not to summarize all recent attempts towards tailoring of materials for selective CO2 capture but to discuss the most fundamental aspects of adsorptive CO2 separation in order to illuminate the “sweet spot” to be explored when electronic structure, polarity, and pore size/geometry are rationally balanced and optimized – just like nature does when exerting selective binding of gases.
406 citations
TL;DR: In this paper, the authors proposed a carbon capture and utilization (CCU) strategy as an alternative approach to addressing the energy penalty problem in CCS, which could render this system suitable for accomplishing chemical transformation of CO2 under low pressure to avoid additional desorption step.
Abstract: Carbon dioxide chemistry (in particular, capture and conversion) has attracted much attention from the scientific community due to global warming associated with positive carbon accumulation. The most widely used chemical absorption technique for carbon capture and storage/sequestration (CCS) would be essentially adopting amino-containing absorbents through formation of C–N bond in terms of mechanistic consideration. However, extensive energy input in desorption and compression process would be a crucial barrier to realize practical CCS. On the other hand, CO2 is very attractive as an environmentally friendly feedstock to replace the hazardous phosgene route for making commodity chemicals, fuels, and materials from a standpoint of green chemistry, whereas the reactions involving CO2 are commonly carried out at high pressure, which may not be economically suitable and also pose safety concerns. The challenge is to develop catalysts that are capable of activating CO2 under low pressure (preferably at 1 atm), and thus incorporating CO2 into organic molecules catalytically. We have proposed a carbon capture and utilization (CCU) strategy as an alternative approach to addressing the energy penalty problem in CCS. The essence of our strategy is to use captured CO2, also considered as the activated form of CO2, which could render this system suitable for accomplishing chemical transformation of CO2 under low pressure to avoid an additional desorption step. Indeed, CO2 could be activated through the formation of carbamate/alkyl carbonate with Lewis basic nitrogen species. In this review, we would like to discuss and update advances on CCU, particularly C–N bond formation with the production of oxazolidinones, quinazolines, carbamates, isocyanates and polyurethanes by using CO2 as C1 feedstock, and CO2 capture by amino-containing absorbents, including conventional aqueous solution of amine, chilled ammonia, amino-functionalized ionic liquids and solid absorbents such as amino-functionalized silica, carbon, polymers and resin, presumably leading to CO2's activation and thus subsequent conversion through C–N bond formation pathway.
397 citations
TL;DR: It is shown that CO2 uptakes can be accurately predicted by using the adsorption data measured at just one temperature, taking into account the temperature invariance of the characteristic curve postulated by the Dubinin theory.
Abstract: The role of micropore size and N-doping in CO2 capture by microporous carbons has been investigated by analyzing the CO2 adsorption properties of two types of activated carbons with analogous textural properties: (a) N-free carbon microspheres and (b) N-doped carbon microspheres. Both materials exhibit a porosity made up exclusively of micropores ranging in size between <0.6 nm in the case of the pristine materials and up to 1.6 nm for the highly activated carbons (47% burnoff). The N-doped carbons possess ∼3 wt % of N heteroatoms that are incorporated into several types of functional groups (i.e., pyrrole/pyridone, pyridine, quaternary, and pyridine-N-oxide). Under conventional operation conditions (i.e., T ∼ 0–25 °C and PCO2 ∼ 0–1 bar), CO2 adsorption proceeds via a volume-filling mechanism, the size limit for volume-filling being ∼0.7–0.8 nm. Under these circumstances, the adsorption of CO2 by nonfunctionalized porous carbons is mainly determined by the volume of the micropores with a size below 0.8 nm...
309 citations
TL;DR: This review provides a critical and in-depth analysis of recent POP research as it pertains to carbon capture, noting areas in which further work is needed to develop the next-generation POPs for practical applications.
Abstract: One of the most pressing environmental concerns of our age is the escalating level of atmospheric CO2 . Intensive efforts have been made to investigate advanced porous materials, especially porous organic polymers (POPs), as one type of the most promising candidates for carbon capture due to their extremely high porosity, structural diversity, and physicochemical stability. This review provides a critical and in-depth analysis of recent POP research as it pertains to carbon capture. The definitions and terminologies commonly used to evaluate the performance of POPs for carbon capture, including CO2 capacity, enthalpy, selectivity, and regeneration strategies, are summarized. A detailed correlation study between the structural and chemical features of POPs and their adsorption capacities is discussed, mainly focusing on the physical interactions and chemical reactions. Finally, a concise outlook for utilizing POPs for carbon capture is discussed, noting areas in which further work is needed to develop the next-generation POPs for practical applications.
271 citations
References
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TL;DR: In this paper, the synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described.
Abstract: The synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described. MCM-41, one member of this family, exhibits a hexagonal arrangement of uniform mesopores whose dimensions may be engineered in the range of - 15 A to greater than 100 A. Other members of this family, including a material exhibiting cubic symmetry, have ken synthesized. The larger pore M41S materials typically have surface areas above 700 m2/g and hydrocarbon sorption capacities of 0.7 cc/g and greater. A templating mechanism (liquid crystal templating-LCT) in which surfactant liquid crystal structures serve as organic templates is proposed for the formation of these materials. In support of this templating mechanism, it was demonstrated that the structure and pore dimensions of MCM-41 materials are intimately linked to the properties of the surfactant, including surfactant chain length and solution chemistry. The presence of variable pore size MCM-41, cubic material, and other phases indicates that M41S is an extensive family of materials.
10,349 citations
TL;DR: In this paper, a family of highly ordered mesoporous (20−300 A) structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media.
Abstract: A family of highly ordered mesoporous (20−300 A) silica structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media. Periodic arrangements of mescoscopically ordered pores with cubic Im3m, cubic Pm3m (or others), 3-d hexagonal (P63/mmc), 2-d hexagonal (p6mm), and lamellar (Lα) symmetries have been prepared. Under acidic conditions at room temperature, the nonionic oligomeric surfactants frequently form cubic or 3-d hexagonal mesoporous silica structures, while the nonionic triblock copolymers tend to form hexagonal (p6mm) mesoporous silica structures. A cubic mesoporous silica structure (SBA-11) with Pm3m diffraction symmetry has been synthesized in the presence of C16H33(OCH2CH2)10OH (C16EO10) surfactant species, while a 3-d hexagonal (P63/mmc) mesoporous silica structure (SBA-12) results when C18EO10 is used. Surfactants with short EO segments tend to form lamellar mesost...
6,274 citations
TL;DR: The current status of the development of CO2 capture technology is discussed in this article, where a wide variety of separation techniques are being pursued, including gas phase separation, absorption into a liquid, and adsorption on a solid, as well as hybrid processes, such as adhesions/membrane systems.
2,058 citations
TL;DR: The unique structure of MCM-41 silicates has provided for extremely attractive properties such as uniform pore sizes greater than 20 A, surface areas exceeding 1000 m2 g−1, and long-range ordering of the pores.
Abstract: The unique structure of MCM-41 silicates (shown in the picture) has provided for extremely attractive properties—uniform pore sizes greater than 20 A, surface areas exceeding 1000 m2 g−1, and long-range ordering of the pores. Recent research in supramolecular-templated mesoporous materials has led to a wide range of compositions, to uses in a variety of catalytic reactions, and to a better control of bulk morphologies.
1,923 citations
TL;DR: In this paper, the authors proposed to use CO2 for environmentally-benign physical and chemical processing that adds value to the process, using CO2 as an alternate medium or solvent or co-reactant or a combination of them.
1,541 citations