Natural Products Derived Porous Carbons for CO2 Capture

As it is now established that global warming and climate change are a reality, international investments are pouring in and rightfully so for climate change mitigation. Carbon capture and separation (CCS) is therefore gaining paramount importance as it is considered one of the powerful solutions for global warming. Sorption on porous materials is a promising alternative to traditional carbon dioxide (CO2 ) capture technologies. Owing to their sustainable availability, economic viability, and important recyclability, natural products-derived porous carbons have emerged as favorable and competitive materials for CO2 sorption. Furthermore, the fabrication of high-quality value-added functional porous carbon-based materials using renewable precursors and waste materials is an environmentally friendly approach. This review provides crucial insights and analyses to enhance the understanding of the application of porous carbons in CO2 capture. Various methods for the synthesis of porous carbon, their structural characterization, and parameters that influence their sorption properties are discussed. The review also delves into the utilization of molecular dynamics (MD), Monte Carlo (MC), density functional theory (DFT), and machine learning techniques for simulating adsorption and validating experimental results. Lastly, the review provides future outlook and research directions for progressing the use of natural products-derived porous carbons for CO2 capture.

Advances in Post-Combustion CO2 Capture by Physical Adsorption: From Materials Innovation to Separation Practice

The atmospheric CO₂ concentration continues a rapid increase to its current record high value of 416 ppm for the time being. It calls for advanced CO₂ capture technologies. One of the attractive technologies is physical adsorption-based separation, which shows easy regeneration and high cycle stability, and thus reduced energy penalties and cost. The extensive research on this topic is evidenced by the growing body of scientific and technical literature. The progress spans from the innovation of novel porous adsorbents to practical separation practices. Major CO₂ capture materials include the most widely used industrially relevant porous carbons, zeolites, activated alumina, mesoporous silica, and the newly emerging metal-organic frameworks (MOFs) and covalent-organic framework (COFs). The key intrinsic properties such as pore structure, surface chemistry, preferable adsorption sites, and other structural features that would affect CO₂ capture capacity, selectivity, and recyclability are first discussed. The industrial relevant variables such as particle size of adsorbents, the mechanical strength, adsorption heat management, and other technological advances are equally important, even more crucial when scaling up from bench and pilot-scale to demonstration and commercial scale. Therefore, we aim to bring a full picture of the adsorption-based CO₂ separation technologies, from adsorbent design, intrinsic property evaluation to performance assessment not only under ideal equilibrium conditions but also in realistic pressure swing adsorption processes.

Efficacies of Carbon-Based Adsorbents for Carbon Dioxide Capture

Carbon dioxide (CO2), a major greenhouse gas, capture has recently become a crucial technological solution to reduce atmospheric emissions from fossil fuel burning. Thereafter, many efforts have been put forwarded to reduce the burden on climate change by capturing and separating CO2, especially from larger power plants and from the air through the utilization of different technologies (e.g., membrane, absorption, microbial, cryogenic, chemical looping, and so on). Those technologies have often suffered from high operating costs and huge energy consumption. On the right side, physical process, such as adsorption, is a cost-effective process, which has been widely used to adsorb different contaminants, including CO2. Henceforth, this review covered the overall efficacies of CO2 adsorption from air at 196 K to 343 K and different pressures by the carbon-based materials (CBMs). Subsequently, we also addressed the associated challenges and future opportunities for CBMs. According to this review, the efficacies of various CBMs for CO2 adsorption have followed the order of carbon nanomaterials (i.e., graphene, graphene oxides, carbon nanotubes, and their composites) < mesoporous -microporous or hierarchical porous carbons < biochar and activated biochar < activated carbons.

Fabrication of resorcinol-based porous resin carbon material and its application in aqueous symmetric supercapacitors

Carbon materials with porous structures with their unique surface area and charge transport properties have been attracting significant attention as electrode materials in renewable energy storage devices. The rapid agglomeration of layered materials during electrochemical processes reduces their shelf life and specific capacitance, which can be prevented by the introduction of suitable pores between the layers. In this study, resorcinol-based porous resin carbon was facilely prepared via a simple carbonization of the potassium salts of resorcinol-potassium resin. The morphology, structure and surface properties of the carbon materials were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption and energy dispersive spectroscopy (EDS). It is proposed that the fast nucleophilic addition between the phenols and formaldehyde produces nano-sized gel particles, followed by carbonization into carbon particles, finally packing to the mesopores. Due to the synergistic effects of the tailored porosity and O-doping, the prepared carbon materials show a high specific capacitance (198 F g⁻¹ for RC700), good capacitance retention (96.5% for RC700) at 2 A g⁻¹ in 6 M KOH and the specific area of RC700 is 540 m² g⁻¹.

Activated preparation of environmentally friendly and sustainable carbon materials and their successful application in supercapacitor devices.

Imine-Linked Polymer Based Nitrogen-Doped Porous Activated Carbon for Efficient and Selective CO2 Capture

The preparation of nitrogen-doped activated carbon (NACs) has received significant attention because of their applications in CO2 capture and sequestration (CCS) owing to abundant nitrogen atoms on their surface and controllable pore structures by carefully controlled carbonization. We report high-surface-area porous N-doped activated carbons (NAC) by using soft-template-assisted self-assembly followed by thermal decomposition and KOH activation. The activation process was carried out under different temperature conditions (600-800 °C) using polyimine as precursor. The NAC-800 was found to have a high specific surface area (1900 m2 g-1), a desirable micropore size below 1 nm and, more importantly, a large micropore volume (0.98 cm3 g-1). NAC-800 also exhibits a significant capacity of CO2 capture i.e., over 6. 25 and 4.87 mmol g-1 at 273 K and 298 K respectively at 1.13 bar, which is one of among the highest values reported for porous carbons so far. Moreover, NAC also shows an excellent separation selectivity for CO2 over N2.

From Azo-Linked Polymers to Microporous Heteroatom-Doped Carbons: Tailored Chemical and Textural Properties for Gas Separation

Heteroatom-doped porous carbons with ultrahigh microporosity were prepared from a nitrogen-rich azo-linked polymer (ALP-6) as a precursor for gas separation applications. Direct carbonization and chemical activation of ALP-6 with ZnCl2 and KOH were successfully applied to obtain three different classes of porous carbons (ALPDCs). Synthetic processes were conducted at relatively mild temperatures (500-800 °C),which resulted in retention of appreciable levels of nitrogen content (4.7-14.3 wt %). Additionally, oxygen functionalities were found to be present in chemically activated samples. The resultant porous carbons feature a diverse range of textural properties with a predominant microporous nature in common. The highest CO2 uptake value of 5.2 mmol g(-1) at 1 bar and 298 K in ALPDCK600 was originated from well-developed porosity and basic heteroatoms (N and O) on the pore walls. The highest heteroatom doping level (12 wt % nitrogen and 20 wt % oxygen) coupled with the high level of microporosity (84%) for ALPDCK500 led to notable CO2/N2 (62) and CO2/CH4 (11) selectivity values and a high CO2 uptake capacity (1.5 mmol g(-1), at 0.15 bar) at 298 K. This study illustrates the effective use of a single-source precursor with robust nitrogen bonds in combination with diverse carbonization methods to tailor the chemical and textural properties of heteroatom-doped porous carbons for CO2 capture and separation applications.

Direct Carbonization of Cyanopyridinium Crystalline Dicationic Salts into Nitrogen-Enriched Ultra-Microporous Carbons toward Excellent CO2 Adsorption

A family of nitrogen-enriched ultramicroporous carbon materials was prepared by direct carbonization of task-specifically designed molecular carbon precursors of cyanopyridinium-based crystalline dicationic salts (CISs). Varying the molecular structure of CISs, large surface area (918 m(2) g(-1)), high N content (20.10 wt %), and narrow distributed ultramicropores (0.59 nm) can be simultaneously achieved on the sample PCN-14 derived from methyl-linked 4-cyanopyridinium D[4-CNPyMe]Tf2N. It therefore exhibited exceptional performance in greenhouse gas CO2 capture, i.e., simultaneously possessing (1) high CO2 adsorption uptakes: 5.33 mmol g(-1) at 273 K, and 3.68 mmol g(-1) at 298 K (both at 1.0 bar); (2) unprecedented selectivity of CO2 versus N2: 156; and (3) a high adsorption ratio of CO2 to N2: 148 (at 1.0 bar). This is the first time such a high selectivity and adsorption ratio over carbon materials has been achieved, which is among the highest values over solid adsorbents.

Nitrogen-doped graphene-supported copper complex: a novel photocatalyst for CO2 reduction under visible light irradiation

Nitrogen-doped graphene immobilized with copper(ii) complex (GrN₇₀₀–CuC) is demonstrated to be an efficient photocatalyst for CO₂ reduction into methanol under visible light irradiation.