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The chemical composition and surface groups of the carbon support affect the adsorption capacity of toluene. To investigate the effect of catalyst substrate on the catalytic performance, two different plant biomasses, banana peel and sugarcane peel, were used as carbon precursors to prepare porous carbon catalyst supports (Cba, Csu, respectively) by a chemical activation method. After decorating PtCo3 nanoparticles onto both carbon supports (Cba, Csu), the PtCo3-su catalyst demonstrated better catalytic performance for toluene oxidation (T100 = 237 °C) at a high space velocity of 12,000 h−1. The Csu support possessed a stronger adsorption capacity of toluene (542 mg g−1), resulting from the synergistic effect of micropore volume and nitrogen-containing functional groups, which led to the PtCo3-su catalyst exhibiting a better catalytic performance. Moreover, the PtCo3-su catalyst also showed excellent stability, good water resistance properties, and high recyclability, which can be used as a promising candidate for practical toluene catalytic combustion. [ABSTRACT FROM AUTHOR]

It's acknowledged that surface chemical and pore structure of adsorbent are main parameters to determine adsorption results. Herein, we prepared zeolitic imidazolate frameworks‐8 (ZIF‐8) with different average sizes (50, 120, and 2200 nm) and demonstrated their specific surface area and pore volume decreased with increasing particle size. ZIF‐8 (ZN) exhibits a large specific surface area (1626.4 m2 g−1) and total pore volume (1.088 mL g−1), but it has been shown to lack the non‐specific adsorption capacity for the adsorbate. Carbonization at 800 °C is proved to be an effective method to expose massive surface nitrogen‐containing functional groups and adjust the aperture to an appropriate pore size range for derived porous carbon of ZIF‐8 (ZCN). High nitrogen content (18.7 at. %) greatly improves the affinity for CO2 and Volatile Organic Compounds (VOCs), as explained by the density functional theory (DFT) calculation results. Meanwhile, particle size influences the pore‐forming results after carbonization directly. Among them, ZC50 generates a certain amount of narrow micropore in range of 0.7–1.0 nm, located in the optimal pore size range of CO2 adsorption calculated by Grand canonical Monte Carlo (GCMC) simulation, thus possessing the largest CO2 adsorption capacity (4.03 mmol g−1 at 25 °C). Besides, ZC120 exhibits more superior mesopore structure that could strengthen multilayer adsorption for VOCs. [ABSTRACT FROM AUTHOR]

The adsorption capacity of porous adsorbent to volatile organic compounds (VOCs) is restricted by pore size distribution and surface functionalities. In this study, we report an effective N‐doped porous carbon synthesis strategy using rationally designed polyimide as precursor and subsequently copper chloride (CuCl2) mild activation. Specifically, by carefully changing the thiourea/urea ratio, polyimide precursors of different configurations can be designed and synthesized, which not only facilitates the transformation to a mesoporous structure, but also slightly enriches the surface heteroatoms. These unique properties result in a series of hierarchical porous carbon with high surface area (2045 m2/g), large mesopore volume (1.32 cm3/g) and rich nitrogen content (8.95 at %). Such carbon consequently shows exceptional static acetone adsorption performance of 768 mg/g (25 °C) and 799 mg/g (15 °C) and fast dynamic transfer rate. The abundant mesoporous structure provides the necessary diffusion channels to shorten the transmission distance and transmission resistance of acetone molecules, thereby contributing to this high acetone adsorption performance. Moreover, electrostatic potential (ESP) charge analysis shows that the doping of nitrogen atoms can significantly change the charge distribution on the sample surface, and enhance the affinity with acetone molecules through electrostatic interaction and Lewis acid‐base interaction [ABSTRACT FROM AUTHOR]

The porous carbon material is widely used as acetone adsorbent. The low‐cost, facile and efficient synthesis method of porous carbon material is of great significance to the removal of acetone. Potassium citrate, a common organic salt, was self‐activated in the current study at the temperatures of 600–900 °C to form porous carbons (KAC−X) with rich microporous structures. The KAC−X showed excellent specific surface area (763–2100 m2 g−1) and oxygen content (5.95–16.29 wt%). The sample obtained at the temperature of 900 °C showed promising acetone adsorption capacities of 8.33 mmol g−1 (15 °C) and 7.27 mmol g−1 (25 °C), respectively. The acetone adsorption results were well fitted by the Langmuir‐Freundlich and Freundlich models. Moreover, the influence of physical structure and oxygen functional group on the acetone adsorption performance was explored. The results showed that: (1) one of the main methods for promoting the acetone adsorption capacity is to increase the specific surface area; (2) the other method is to increase the optimal pore volume, and the optimal pore size is 2–5 times of the acetone molecule diameter; (3) carboxyl and carbonyl groups can significantly increase the adsorption affinity between acetone molecule and KAC−X, and play an auxiliary role on the acetone adsorption. This study provides guidance for the facile synthesis of porous carbons from organic salt for the sake of acetone adsorption. [ABSTRACT FROM AUTHOR]

Nitrogen‐enriched porous carbon material with large specific surface area is of great demand in various applications. Herein, CuCl2 is adapted as a mild activator to transform the mixture of soybean meal and melamine cyanurate into a novel type of nitrogen‐enriched hollow porous carbon microspheres with well‐defined hierarchically structure. Excitingly, this mild activation agent not only helps generating porous structure, but also helps increasing the nitrogen content (mainly pyrrolic‐N) of products. The product NPC‐800‐4 exhibits the highest specific surface area (1672.45 m2 g−1) while a pretty high nitrogen content (13.09 at%). The NPC‐800‐4 sample performs the largest toluene and acetone adsorption capacity (818.46 mg g−1 and 758.87 mg g−1 respectively). Furthermore, Grand canonical Monte Carlo (GCMC) and density functional theory (DFT) calculations prove that the introduction of nitrogen functional groups can heighten the polarity of carbon framework and the electrostatic interaction, thus enhance the acetone adsorption capacity. [ABSTRACT FROM AUTHOR]

To investigate the effects of oxygen‐containing functional groups on the adsorption of volatile organic compounds (VOCs) with different polarity, oxygen‐rich porous carbon materials (OPCs) were synthesized by heat treatment of glucose/potassium oxalate material. The carbon material had a large specific surface area (1697 m2 g−1) and a high oxygen content (18.95 at.%). OPC exhibited high adsorption capacity of toluene (309 mg g−1) and methanol (447 mg g−1). The specific surface area and total pore volume determined the adsorption capacity of toluene and methanol at the high‐pressure range, while the oxygen‐containing groups became the main factor affecting the methanol adsorption at the low‐pressure range due to the hydrogen bond interaction through the density functional theory (DFT) calculations. This study provides an important hint for developing a novel O‐doped adsorbent for the VOCs adsorption applications and analyzing the role of oxygen‐containing groups in the VOCs adsorption under the low‐pressure range. [ABSTRACT FROM AUTHOR]

This study focused on the role of pore structures and nitrogen surface functional groups in the formaldehyde (HCHO) adsorption on the carbonized resin‐based materials (UFC). After comparing the optimal sample UFAC‐700 obtained by the activation of UFC at 700°C with the commercial activated carbon (CAC) and other UFC, the HCHO adsorption capacity for UFAC‐700 (12.30 mg g−1) is more than three times and 10 times of that for CAC and UFC, respectively. Abundant pore structures could provide more adsorption sites for the initial stage of HCHO adsorption. Moreover, according to the density functional theory (DFT) calculations, pyrrolic‐N could enhance the adsorption energy and polar interaction of HCHO due to electrostatic force between the positively charged H attached to the nitrogen group and the negatively charged O atoms in the HCHO molecule. This study introduced a novel way to specifically design the surface modifications for volatile organic compounds (VOCs) adsorption. [ABSTRACT FROM AUTHOR]

The porous carbon is considered to be one of the most suitable materials for volatile organic compounds (VOCs) adsorption and separation. Revealing the adsorption behavior and molecular interaction mechanism is of great significance for the preparation and synthesis of porous carbon adsorbents. Herein, we investigated detailed mechanistic effects of graphitization degrees and surface oxygen heteroatoms of porous carbon on their benzene and ethanol adsorptive separation performance by combining experiments and theoretical calculations. The results show that graphitized carbon surface has a stronger van der Waals interaction with benzene molecules compared to the disordered carbon surface, and thus exhibit a higher benzene adsorption performance and benzene/ethanol selectivity. While the introduction of oxygen functional groups enhances electrostatic affinity of porous carbon surface, resulting in higher ethanol adsorption capacity and ethanol/benzene selectivity under the entire pressure range. Subsequent theoretical calculations studied the adsorption behaviors of benzene and ethanol molecules in porous carbon models (with different graphitization degrees and oxygen contents) from the perspective of the weak interactions, and found the different molecular configurations of benzene and ethanol is the main leading cause of their different adsorption preferences. This study provided mechanistic insights on how the graphitization degrees and oxygen heteroatoms affected the capture and separation properties of porous carbon, which would further provide a rational alternative strategy in the preparation and synthesis of porous carbons for the effective gas mixture capture and separation. • The vital role of graphitization degrees and surface oxygen heteroatoms on VOCs adsorptive separation is proved. • Provide a molecular perspective on the adsorption behavior of VOCs in porous carbons. • The intrinsic enhancement mechanism in adsorption and separation process was clarified. • Provide a rational alternative strategy in preparation and synthesis of porous carbons. [ABSTRACT FROM AUTHOR]

Will the CO 2 capture be affected by the N-doping? This question remains conflict due to the effect of oxygen content in N-doped porous carbons on CO 2 uptake has not been systematically investigated. Herein, the effects of N-free and N-doped porous carbons on CO 2 uptake were investigated by experiments and theoretical calculations. To elucidate the relative influences of nitrogen functional groups, we synthesized a series of carbons without or with N-doping (2.73–9.44% N) by varying the synthesis conditions. Experimental results show that the introduction of oxygen and nitrogen into carbon framework improves CO 2 capture in porous carbons (PCs) and N-doped porous carbons (NPCs). Among these samples, the NPC600 exhibits an exceptionally high CO 2 adsorption capacity (5.01 mmol g−1 at 1 bar and 25 °C). Based on the theoretical calculations, the introduction of nitrogen into carbon framework with high oxygen content further enhances electrostatic interaction for CO 2 adsorption. Moreover, the doping of nitrogen to carbon framework also has a greater effect on both the selectivity for CO 2 /N 2 and the isosteric heat of CO 2 adsorption. It is predicted that this investigation will eliminate any ambiguities and better explain the influence of N-doping on CO 2 capture. • We synthesized a series of carbons without N-doping and with N-doping. • The porous carbons exhibited the superior CO 2 adsorption capacity. • O-doping and N-doping improve CO 2 adsorption. • The interaction between functional groups and CO 2 was elucidated by GCMC calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] The influence of different pore size and oxygen groups for porous carbons on acetone adsorption at different pressure was studied by using experimental data and theoretical calculation, and the results were applied to prepare carbon-based adsorbents with superior adsorption capacity. First, we successfully prepared five types of porous carbons with different gradient pore structure but similar oxygen contents (4.9 ± 0.25 at.%). We found that the acetone uptake at different pressure depends on the different pore sizes. Besides, we demonstrate how to accurately decompose the acetone adsorption isotherm into multiple sub-isotherms based on different pore sizes. Based on the isotherm decomposition method, the acetone adsorption at 18 kPa is mainly in the form of pore-filling adsorption in the pore size range of 0.6–2.0 nm. When the pore size is greater than 2 nm, the acetone uptake mainly depends on the surface area. Second, porous carbons with different oxygen content, similar surface area and pore structure were prepared to study the influence of oxygen groups on acetone adsorption. The results show that the acetone adsorption capacity is determined by the pore structure at relatively high pressure, and the oxygen groups only slightly increase the adsorption capacity. However, the oxygen groups can provide more active sites, thereby enhancing acetone adsorption at low pressure. [ABSTRACT FROM AUTHOR]

Porous carbon is an ideal adsorbent for the elimination of volatile organic compounds (VOCs) attributed to their price, availability and excellent adsorption capacity. However, there are significant variation in the adsorption capacity and adsorption selectivity of different precursors for VOCs under humid conditions after modification because of the differences in their own structural properties. In this study, graphitized hydrophobic porous carbon with excellent specific surface area was successfully synthesized by selecting bamboo fiber, maize, coconut husk and coal as precursors and potassium hydroxide as an activator. Among them, the dynamic adsorption capacity of benzene in the sample with bamboo fiber as precursor was maintained at 74.7 % under the high humidity condition (RH90 %) compared with the dry state (RH0 %). Grand Canonical Monte Carlo (GCMC) simulations and weak interaction force analyses showed that enhanced dispersion attraction between graphitized carbon surfaces and benzene molecules in comparison to disordered carbon surfaces. The existence of oxygen functional groups enhanced the interaction between porous carbon and water through hydrogen bonding leading to preferential adsorption of water molecules, which resulting in the decrease of their adsorption performance in wet condition. This research provided theoretical and experimental views of the effects of graphitization and oxygen functional groups on the competitive adsorption capture of benzene and water by porous carbon, which further provided a reliable approach to synthesizing porous carbon with high adsorption capture for benzene removal in high humidity environments. [Display omitted] • Screening for efficient activation and graphitization of the precursors for porous carbon. • Excellent benzene adsorption retention (74.7 %) in humid environments (RH90 %). • Benzene adsorption selectivity affected by graphitization and oxygen content. • Enhanced dispersion facilitates the adsorption selectivity of benzene on sp2 carbon. • Hydrogen bonding impairs the adsorption selectivity of benzene and water. [ABSTRACT FROM AUTHOR]

Constrained by the unsatisfactory physical adsorption capacity and the low carbon yield from chemical activation, practical utilization of carbon materials for CO 2 capture and separation (CCS) remains a huge challenge. Herein, we proposed a novel in-situ activation methodology to prepare a category of porous carbon monoliths in which the potassium ion activation sites are evenly introduced through acid-base reaction, contributing to the high carbon yield, abundant ultramicropores as well as rich nitrogen content. Tested at adsorption temperatures of 0, 25 and 40 °C, the as-prepared carbon monoliths display remarkable static CO 2 uptake (7.1, 5.0 and 3.7 mmol/g, respectively) and excellent selective adsorption ability in dynamic breakthrough experiment with a binary mixture of CO 2 /N 2 (68, 63 and 67, respectively). Along with the experiments, the CO 2 adsorption mechanism was determined by calculating the adsorption density and adsorption energy on slit pore with various pore sizes and surface functionalities using grand canonical Monte Carlo (GCMC) simulation. The narrow micropores can significantly and effectively increase the CO 2 adsorption capacity, while the functional groups played the second role. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A kind of activated carbon with alterable phosphorus functional groups and stable structure was synthesized. • The chemical functional groups influence coefficient (A C) was proposed. • The performance of TSA and PSA can be predicted by the chemical functional groups influence coefficient (A C) accurately. • The factors affecting curve characteristics in TSA and PSA and their mechanisms were revealed respectively. • The main factors causing the attenuation of activated carbon in TSA and PSA were revealed respectively. Volatile organic compounds (VOCs) emissions cause serious health problems and environmental pollution, and modified activated carbon is widely used in the treatment of VOCs pollution. Methanol was selected as adsorbate and activated carbon with alterable phosphorus functional groups was synthesized as adsorbent. In the absence of the influence of the physical properties, the chemical functional groups influence coefficient (A C) was proposed, which can be used to analysis and predict the influence of chemical functional groups specially. The results show that the performances including adsorption capacity and enrichment ratio are positively related to the A C whether in temperature swing adsorption (TSA) or pressure swing adsorption (PSA). By comparison, the adsorption capacity of PSA is greater than that of TSA because of the higher efficiency caused by faster cycle. Further research on process showed that the curve character of TSA, including breakthrough time and equilibrium time, is highly related with A C , but the curve character of PSA is mainly depended on the state of activated carbon. Therefore, the attenuation of TSA is mainly caused by the change of chemical functional groups, while the attenuation of PSA is mainly caused by the failure of activated carbon. [ABSTRACT FROM AUTHOR]

• Porous carbon with superior uptake capacity for methanol and acetone was prepared. • The influence of precursor-to-activator ratio on pore development was investigated. • The impact of pore size and O/N groups on methanol and acetone adsorption was study. • The separation mechanism of azeotrope by pore size and pressure was revealed. The adsorption and separation of methanol and acetone are crucial for environmental protection and recycling. However, the separation of methanol and acetone azeotropes using carbon-based materials remains challenging, and the underlying mechanism is still unclear. Here, we propose the synthesis of porous carbon (NaOCs) using benzimidazole as a precursor and NaOH as an activator. With the increase of the proportion of NaOH and benzimidazole, the activation reaction was intensified, leading to the formation of numerous mesopores. NaOCs exhibit a maximum specific surface area (S BET) of 3084 m2/g, and has extremely high adsorption capacity of methanol (56.9 mmol/g at 13 kPa) and acetone (34.6 mmol/g at 18 kPa) at 25 °C. The results of experiments and molecular simulations indicate that the saturation adsorption capacity of methanol and acetone is determined by micropores and narrow mesopores at 25 °C, whereas the adsorption capacity at relatively low pressure is primary determined by ultramicropores and oxygen group. Furthermore, for methanol-acetone azeotropes separation, the acetone/methanol selectivity at low pressure depends on carbon surface polarity and ultramicropore, while methanol/acetone selectivity at high pressure depends on micropores of 1–2 nm. Our findings provide insights into the design and further development of adsorbents for VOCs adsorption and azeotrope separation applications. [ABSTRACT FROM AUTHOR]

• Oxygen and nitrogen co-doped porous carbon/MgO (ONPC@MgO) composites were synthesized. • Acetone is captured by O/N functional groups and MgO by monolayer adsorption at low pressure. • Acetone is adsorbed on the surface of carbon and MgO by multilayer adsorption at high pressure. • Adsorption mechanism between acetone and ONPC@MgO composites is elucidated by experimental and DFT methods. The amount of anthropogenic volatile organic compounds (VOCs) emission keeps increasing worldwide, and it urges the development of VOC emission reduction technology. Efficient and environmentally friendly adsorption technology is receiving more interest, and carbon-based materials have attracted enormous attention for VOC capture. However, the poor adsorption capacity and cycling stability still hinder their application. Moreover, the mechanism of adsorption behavior between functionalized carbon surfaces and VOCs has not been investigated in detail. Herein, we report a sustainable and cost-effective method for the anchoring of the MgO nanoparticle onto O/N co-doped porous carbon derived from waste biomass (denoted as MgO@ONPC). The optimized 7%MgO@ONPC composite exhibited an exceedingly high acetone adsorption capacity (859 mg g−1 at 25 °C, 18 kPa) and excellent cycling stability (95.2% capacity retention over 10 cycles). Acetone dynamic breakthrough tests showed that the adsorption capacity of 7%MgO@ONPC composite at 10% breakthrough level (10% BT) and 100% BT was 384 and 508 mg g−1, respectively (in terms of PC: 3.9 × 10−3 and 5.2 × 10−2 mol kg−1 Pa−1, respectively). Isotherm model fitting and quantum chemistry calculation studies indicated O/N functional groups and MgO nanoparticles can significantly improve the acetone monolayer adsorption at low relative pressures due to hydrogen bonds and electrostatic interaction. Highly active MgO nanoparticles and pore structure characteristics are found to be determinative factors for acetone adsorption at high relative pressure. [ABSTRACT FROM AUTHOR]

• Building a prediction model for acetone adsorption by porous carbon by machine learning. • The N/O group and V m determine the acetone adsorption at relatively low pressure. • The adsorption capacity at relatively high pressure is determined by V t. • Acetone adsorption mechanism by pore size and N/O groups was revealed by GCMC. The scientific design and preparation of porous carbon with high VOCs (such as acetone) adsorption capacity are crucial for waste gas treatment. However, it is still challenging to explain the microscopic mechanism of acetone uptake on porous carbon because of the different adsorption conditions, as well as various chemical properties and different pore structures of porous carbon. Here, the prediction model of the adsorption conditions, nitrogen/oxygen groups and pore structures on acetone adsorption capacity was established by machine learning, and the contribution of the nitrogen/oxygen groups and pore structures of porous carbons to the acetone adsorption capacity at different adsorption pressures was discussed. The results display that the nitrogen/oxygen groups and micropore volume are the main factors affecting the adsorption capacity of acetone at relatively low pressure, while the adsorption capacity at relatively high pressure is determined by total pore volume. Subsequently, three kinds of porous carbon with different oxygen content and gradient pore size distribution were synthesized, and acetone adsorption isotherms were tested. The effects of chemical properties and pore structure on acetone adsorption at different pressure were studied, and the results were consistent with those of machine learning. However, the results are challenging to illustrate the effect of single pore size and functional group type on acetone adsorption performance. Finally, molecular simulation was used to calculate acetone adsorption isotherms with various nitrogen/oxygen groups and different pore sizes, further revealing the adsorption mechanism of acetone with nitrogen/oxygen groups and pore size. Based on machine learning and molecular simulation results, new insights into the adsorption behavior of acetone were revealed, providing theoretical support for the sustainable development of carbon-based adsorbents for acetone waste gas treatment. [ABSTRACT FROM AUTHOR]

• The pore size of BICs is controllable. • BICs have a maximum total pore volume of 2.42 cm3/g. • The adsorption capacity for benzene and methanol reaches 22.19 and 52.56 mmol/g. • BICs exhibit excellent benzene/methanol separation performance (∼30.13). • Surface heterogeneity induced by heteroatoms is revealed through DFT and GCMC simulation. Porous carbon materials are good adsorbent candidates for removing volatile organic compounds (VOCs) due to their reliability and cost-effectiveness. Especially, the pore size distribution (PSD) of porous carbon materials plays a critical role in VOCs adsorption and separation. In this study, we present benzimidazole-derived porous carbons (BICs) with controllable pore size and oxygen/nitrogen heteroatoms. The pore size is controlled by adjusting the reaction degree of inorganic salt (K 2 CO 3) and nitrogen-containing groups in the system. The tunable pore size distribution makes BICs highly efficient for the adsorption and separation of VOCs. BIC-3-900 exhibits a dominant pore size distribution of 3.0–4.0 nm and an exceptionally high total pore volume of 2.42 cm3/g, leading to ultra-high adsorption capacities for benzene and methanol (22.19 and 52.65 mmol/g, respectively) at 293 K. In addition, BIC-1-700 dominated by the micropore size is more favorable for adsorbing low-concentration small molecule VOCs (with a dynamic adsorption capacity of 4.21 mmol/g for methanol at 3800 ppm). In terms of the adsorptive separation performance, BIC-1-900 has an efficient benzene/methanol selectivity (∼30.13) due to its PSD (1.2–2.0 nm) which was more favorable for capturing low-concentration benzene. Moreover, both experimental and simulation (GCMC and DFT) results demonstrate that the abundant N/O heteroatoms doping in BIC-1-700 results in charge heterogeneity and stronger electrostatic affinity for polar VOCs molecules. Herein, our findings suggest that BICs with controllable pore size and oxygen/nitrogen heteroatoms have significant potential in practical VOCs capture and separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six representative oxygenated VOCs and aromatic VOCs were selected. • The effects of pore sizes and functional groups on VOCs adsorption were investigated. • Oxygenated VOCs adsorption depends on micropores and heteroatom at low pressure. • Aromatic VOCs adsorption depends on different pore sizes at different pressures. • Provide guidance for preparation of adsorbents for oxygenated and aromatic VOCs adsorption. It is very difficult to design and prepare carbon-based adsorbents due to the wide variety and great differences in physical and chemical properties of VOCs. Here, representative oxygenated VOCs (methanol, ethanol and acetone) and aromatic VOCs (benzene, toluene and p-xylene) were selected. The influences of pore sizes and nitrogen/oxygen groups of porous carbon on different VOCs adsorption were investigated by molecular simulation. The results display that for oxygenated VOCs, the adsorption capacity is determined by micropores and functional groups at relatively low pressure, while the adsorption capacity mainly depends on pore structure at relatively high pressure. For aromatic VOCs, the influence of nitrogen and oxygen groups on adsorption capacity is limited, and the adsorption capacity is determined by the pore structure. Then, a series of nitrogen and oxygen-doped porous carbon (NOCs) were prepared. Taking methanol and benzene as examples, the effects of heteroatoms and pore size on VOCs adsorption were studied. The experimental results were consistent with the theoretical calculation. The above results reveal the influence of functional groups and pore structure on the adsorption properties of VOCs from the perspective of experiment and theoretical calculation, which provides a basis for the further design and development of carbon-based VOCs materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The VOCs adsorption isotherms of alkali metal-doped carbon were calculated. • The VOCs adsorption capacity on PC-LiO increased by 924 and 29 times compared with PC (0.2 kPa). • The VOCs adsorption capacity on PC-Rs are determined by the pore structure at relatively high pressure. • The intrinsic mechanisms of alkali metal groups to VOCs adsorption were clarified. • Provide theoretical guidance for preparation of VOCs adsorbents. The doping of alkali metal groups (LiO-, NaO- and KO-) into porous carbons (PC) for acetone and methanol adsorption were studied for the first time by Grand Canonical Monte Carlo (GCMC) simulation and Density Function Theory (DFT). The results indicate that all alkali metals groups can significantly improve the methanol and acetone adsorption capacity at relatively low pressure (0.2 kPa). Especially the methanol and acetone adsorption capacity on PC-LiO increased by 924 and 29 times compared with PC, respectively. These results are mainly attributed to the stronger adsorption energy and electrostatic interaction of PC-LiO on VOCs molecules than that of PC. At relatively high pressure, the alkali metals groups have no obvious effect on the methanol and acetone adsorption capacity, but are determined by the pore structure due to the pore-filling adsorption mechanism. Besides, the methanol/acetone selectivity of PC-LiO is much higher than that of PC, indicating that the LiO-doped PC can improve methanol and acetone separation. The above results show that alkali metal-doped porous carbon has been proved to be one of the promising adsorbents for methanol and acetone adsorption capacity at relatively low pressure, and provides an effective alternative strategy for the design and screening of VOCs adsorbents. [ABSTRACT FROM AUTHOR]

Adsorption has been proved to be an effective control method of Volatile organic compounds (VOCs). However, the design of porous carbon materials with a high VOCs adsorption performance is still a challenging topic. Herein, we proposed a novel material preparation path, namely, the synthesis of porous carbon materials guided by molecular simulation. Firstly, the optimal adsorption pore size of VOCs was calculated by grand canonical Monte Carlo (GCMC) simulation, and then cork based porous carbon with the optimal pore size controlled by urea and KOH was prepared. The sample treated at 900 °C had a specific surface area of 1940 m2/g, a total pore volume of 1.27 cm3/g, a micropore volume of 0.71 cm3/g, which showed an excellent VOCs adsorption performance at 25 °C. Specifically, the dynamic adsorption capacity of acetone and toluene were 6.1 mmol/g and 5.4 mmol/g, and the static adsorption capacity of acetone and toluene were 17.5 mmol/g (18 kPa) and 9.5 mmol/g (3 kPa), respectively. In terms of the pore size distribution, the contribution of the optimal pore sizes to the adsorption process was estimated to be about 69% for acetone and 59% for toluene. Besides, the relationship between the optimal pore size and its adsorption capacity was explored by mathematical methods, which showed a highly linear one. This study provides a novel idea for the design and optimization of excellent adsorbent materials. [Display omitted] • Optimal adsorption pore size of VOCs was calculated by GCMC simulation. • Cork based porous carbon with the optimal pore size was prepared. • NPC-900 showed an excellent VOCs adsorption performance at 25 °C. • The contribution of the optimal pore size to the adsorption process was estimated. • The relationship between optimal pore size and adsorption capacity was explored. [ABSTRACT FROM AUTHOR]

The low energy consumption and facile activation methods are of great significance to synthesize porous carbon fibers. In this work, polyacrylonitrile-based porous carbon fiber (ACFN-X) was synthesized by sodium amide activation at the temperature ranges of 400–600 °C. The characterization of ACFN-X proves the formation of porous structure and N–O doped surface. Acetone was used as an adsorbate to explore the adsorption performance of the ACFN-X samples. The maximum acetone adsorption capacity is 4.80 mmol g−1 (at 25 °C, 18 kPa). The experimental results are well fitted by the Freundlich model, Sips model and Langmuir model to express the equilibrium adsorption, which indicates that the ACFN-X has a positive adsorption cooperativity on the acetone. Besides, the pseudo-first-order and pseudo-second-order kinetic model could well describe the kinetic processes. The rate constant k 2 is mainly affected by the positive effect of the nitrogen functional groups. Moreover, the coupling roles of pore structure and functional groups on acetone adsorption performance were also explored. The results show that micropores play a crucial role in acetone adsorption. Nitrogen functional groups play a promoting role in micropores, and the addition of the pyrrolic exhibits the highest affinity with acetone molecules in the presence of oxygen functional groups. This study provides ideas an option for the preparation of porous carbon fibers as VOCs adsorption. [Display omitted] • Porous carbon fibers from low-temperature sodium amide activation were synthesized. • Micropores play a major role in acetone adsorption. • The rate constant k 2 is mainly affected by the positive effect of the nitrogen functional group. • The pyrrolic in micropores exhibits the highest affinity with acetone molecules in the presence of oxygen functional groups. [ABSTRACT FROM AUTHOR]

• The vital role of oxygen content in determining VOCs adsorption is proved. • The carboxyl groups favors the VOCs adsorption and separation the most. • The remarkable capacity is mainly attributes to the strong electrostatic interaction. • The aggregation of methanol molecules are responsible for the high selectivity. • No obvious synergistic effect between oxygen functional groups was found. Heteroatoms doping brings a burgeoning class of adsorbents for the removal of volatile organic compounds (VOCs). It is of great importance to reveal the molecular interaction and adsorption mechanism on account of the nanoscale nature of adsorption. Herein, we combined adsorption experiments and theoretical calculations (using porous carbon as adsorbent and graphene as computational model) to reveal the influence of doping oxygen atoms on the surface heterogeneity and the VOCs adsorption performance, and to investigate the synergistic effect of oxygen-containing functional groups. The results show that oxygen doping can significantly change the charge distribution and improve the adsorption and separation of methanol and acetone (the selected representative of VOCs). Among various oxygen-containing functional groups, the carboxyl doped surface displays the largest theoretical adsorption capacity of methanol (36.74 mmol/g) and acetone (18.35 mmol/g) and the highest selectivity (16.11 at 0.1 kPa). Specifically, the doped oxygen containing groups significantly changed the charge distribution on the carbon surface (e.g., –0.50 to 0.43 e for carboxyl group), and enhanced the electrostatic interaction between the surface and VOCs molecules, thereby increasing the adsorption capacity. Moreover, the stronger binding energy between the oxygen-functionalized surface and methanol contributed to the preferential adsorption of methanol on the oxygen active sites, leading to the aggregation of methanol molecules, which is responsible for the high selectivity. Meanwhile, no obvious synergistic effect between oxygen functional groups was found. This study provides fundamental understanding of the role of oxygen-containing groups toward VOCs adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous carbon and metal heteroatom are implanted into MIL-101 framework. • The 20%Mg@MIL-101/PC has an acetone capture capacity up to 1309 mg g−1 at 288 K. • Porous carbon effectively improves the surface dispersion force of the MIL-101. • Mg replaces the Cr atom to format Mg–O bond in the crystal core. • Adsorption mechanism between acetone and Mg@MIL-101 is elucidated by DFT. The development of highly active and stable adsorbents for volatile organic compounds (VOCs) capture is an efficient solution to address global problems in atmospheric pollution and environmental health. Herein, a metal–organic framework derived adsorbent consisting of metal heteroatom (Mg, Cu and Co) and porous carbon supported on MIL-101 framework is designed to enable high affinity for adsorbing acetone. The doped metal heteroatoms are homogeneously dispersed in the MIL-101/PC octahedron. The modification of doped metal heteroatoms improves the acetone adsorption capacity of the MIL-101/PC composite at low relative pressure. Importantly, the optimized 20%Mg@MIL-101/PC composite not only shows higher surface area (3838 m2 g−1) and pore volume (2.24 mL g−1) than MIL-101/PC, but also creates stronger active adsorption sites for acetone. As a consequence, the acetone adsorption capacity of 20%Mg@MIL-101/PC reaches 1309 mg g−1 at 288 K and 18 bar, and the saturated adsorption capacity decreases by only 12% over 10 adsorption–desorption consecutive cycles. Consequently, quantum chemistry calculation method is performed to better understand the microscopic adsorption behavior of acetone. The results of density functional theory (DFT) calculation show that the introduction of Mg can significantly improve the dipole moment of MIL-101 core and reduce its gap band energy, thus enhancing the electrostatic interaction with acetone molecule. [ABSTRACT FROM AUTHOR]

The N-O co-doped porous carbons with high specific surface areas and hierarchical pore structures were synthesized by KOH activation method using melamine urea-formaldehyde resin as the carbon precursor. The adsorption properties of toluene on all the samples were studied by experiments, density functional theory (DFT) calculation and grand canonical Monte Carlo (GCMC) simulation. Results showed N-O co-doped porous carbon exhibited a great specific surface area (2784.53 m2 g−1), a desirable pore volume (1.83 cm3 g−1), a high nitrogen (16.16%) and oxygen content (15.75%), and especially an excellent toluene adsorption performance (813.6 mg g−1, 25 °C). By correlating the adsorption capacity with physical and chemical property parameters, the main factors affecting the toluene adsorption were pore size and specific surface area. Furthermore, according to the theory calculation, the interaction between toluene and toluene can be improved by the N-O functional group and the multilayer adsorption can be formed. Considering this, we concluded that the optimal adsorption pore size of N-O co-doped porous carbons was 3–7 times as much as the toluene dynamic diameter. Such optimal adsorption pores not only provided a pathway and adsorption sites for toluene, but also had higher adsorption capacity of toluene. This study can be used to promote the molecular design of adsorbent of heteroatomic doping with an optimal adsorption pore size. [Display omitted] [ABSTRACT FROM AUTHOR]

• A cost-effective strategy to develop low-cost biomass-based carbon materials were prepared. • The highest surface area of hierarchical porous carbon is up to 3936 m2 g−1. • The porous carbon exhibits record-high acetone and methanol adsorption capacity at 25 °C. • The oxygen groups can enhance the acetone and methanol uptake at relatively low pressure. • The narrow micropore determines the acetone/methanol selectivity at relatively low pressure. In this study, biomass-based hierarchical porous carbons (HPCs) were synthesized by developing a cost-effective strategy that combines pyrolysis with KOH activation. The highest surface area of HPCs is up to 3936 m2 g−1, which presents record-high acetone (26.1 mmol g−1 at 18 kPa) and methanol (46.9 mmol·g−1 at 15 kPa) adsorption capacity at 25 °C. Based on experiments and molecular simulations, the total pore volume mainly determines adsorption amount of acetone and methanol at relatively high pressure. However, the oxygen groups can provide adsorption sites for acetone and methanol at relatively low pressure, which is attributed to electrostatic interaction between gas molecules and carbon frameworks. Additionally, the narrow micropore determines the acetone/methanol selectivity at relatively low pressure, and the oxygen groups have no benefit effect on acetone/methanol selectivity. Therefore, this work provides theoretical and experimental support for the design, preparation, and application of VOCs adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synergistic effects of surface functional groups and pore sizes were elucidated. • The capture property of CO 2 at low pressures and high pressures was investigated. • The intrinsic enhancement mechanism in adsorption capacity was clarified. • Provide an alternative strategy in preparation and synthesis of carbon materials. In this work, the capture property of CO 2 molecules on M-doped (M = N, P, S, and O) functionalized-graphite surfaces with different pore sizes (0.8–5.0 nm) were investigated by using grand canonical Monte Carlo simulation (GCMC) and density functional theory (DFT). The synergistic effects of surface functional groups and pore sizes on the adsorption behavior of CO 2 on functionalized surfaces were elucidated. At low pressures, the surface functional groups presented a significant enhancement on CO 2 adsorption performance, regardless of the pore size. At high pressures, for pore size being larger than 1.0 nm, the surface functional groups made an important contribution on the saturated CO 2 adsorption capacity. Among all the surface functional groups, the P-doped functionalized-graphite surfaces had a prominent influence on CO 2 uptake owning to the strong electron-gaining/donating capacity and high adsorption energies. At low pressures, G-CO─PO(OH) 2 exhibited a superior CO 2 capture performance (6.0 mmol/cm3 for 1.0 nm pore) at 16 kPa. At high pressures, G-C 3 ─P has the maximum CO 2 uptake (15.3 mmol/cm3 for 1.0 nm pore) at 300 kPa. Based on the comprehensive research of various polar functional groups and pore sizes, this study clarified the intrinsic enhancement mechanism in adsorption capacity of functionalized-graphite surfaces, which would pave an alternative way in the design and synthesis of carbon materials for gas capture. [ABSTRACT FROM AUTHOR]

Biomass-based porous carbon materials, as promising CO 2 adsorbents, have demonstrated their superiority and inherent potential. However, most of the previous reports simply attributed the unprecedented CO 2 capture of porous carbon to the presence of abundant narrow micropores of less than 0.7 nm. Here, we have successfully prepared microporous carbons with analogous textural properties and oxygen functional groups by KOH activated from hydrothermally treated biomass. Based on the experimental results and theoretical calculations, we have found that the oxygen-containing functional groups on porous carbons are critically sensitive to CO 2 uptake, especially with carboxyl and hydroxyl groups. We can roughly estimate that oxygen groups and pore structure of OC700 contribute 37% and 63% respectively to the CO 2 capture, which can be elucidated by grand canonical Monte Carlo (GCMC) simulations. The introduction of oxygen functional groups into porous carbon materials firmly grasps CO 2 through electrostatic interactions by density function theory (DFT) calculations. These oxygen groups provide new adsorption sites for the efficient CO 2 capture. The OC700 achieves an extremely high CO 2 adsorption capacity of 8.0 mmol g−1 and 4.8 mmol g−1 at 0° C and 25 °C (1 bar), respectively. [ABSTRACT FROM AUTHOR]

• Nitrogen doped carbon materials with hierarchical porous structure and ultrahigh S BET were prepared. • N-functional groups provided a stronger polarity for adsorbent and enhanced the adsorption of VOCs. • The Langmuir-Freundlich model was found to fit quite well with the adsorption equilibrium data. • Adsorption mechanism of VOCs was clarified by experimental and DFT methods. The objective of this study was to assess the VOCs (methanol and toluene) adsorption capacity of doped porous carbon materials (resin-based carbon and bamboo char) by experiments and theoretical calculations. Results showed N-doped porous carbon material exhibited a high specific area (2293.2 m2 g−1), a desirable microporocity (0.90 cm3 g−1), and a large adsorption capacity for methanol (915.3 mg g−1) and toluene (622.9 mg g−1), which were better than those derived from bamboo char. According to the density functional theory calculation, in terms of different N-containing functional groups, the results showed that methanol adsorption was dominated by the electrostatic interaction between the carbon surface and methanol, while toluene was mainly trapped through π-π dispersive interaction with the aromatic ring moving to the carbon surface. This study gave us hints to conduct the doping of polarized element to adsorb polar gases. [ABSTRACT FROM AUTHOR]

• Removal of indoor HCHO could be enhanced by doping optimized elements. • The static/dynamic adsorption trends of doped materials to HCHO were consistent. • The adsorption energy of doped carbon materials to HCHO was P > S > N by DFT calculations. • Surface functional groups played a secondary important role in the HCHO adsorption. The objectives of this study were to assess the formaldehyde (HCHO) adsorption capacity of doped porous carbon by experiments and theoretical calculations. Nitrogen, sulfur or phosphorus containing porous carbons were prepared with different precursors by activation with KOH at 700 °C and compared with commercial activated carbon (CAC), and used as the low HCHO concentration adsorbents in dry (dynamic) and wet (static) conditions. Results showed that the HCHO adsorption capacity of AC-N (2418.20 m2 g−1) for dynamic (13.60 mg g−1) and static (1.43 mg g−1) was greater than that of AC-S, CAC and AC-P. The specific surface area and the micropores volume were expected to markedly influence the adsorption capacity of HCHO. According to the DFT calculation, the adsorption energy of surface functional groups of phosphorus (−0.53296 eV) was the highest, followed by sulfur (−0.52646 eV) and nitrogen (−0.41246 eV), which indicated hydrogen bond interaction played an important role in the adsorption. In the GCMC slit model, the size of slit pores was positively correlated with the adsorption amount of HCHO. With the increase of the adsorption pressure, the surface functional groups had little effect on the adsorption of HCHO under the same size of the slit pores. Accordingly, for the high HCHO adsorption capacity, specific surface area and pore volume are the primary determinant, while surface functional group is the secondary determinant. This would provide a useful theoretical reference for the doping of polarized activated carbon to adsorb polar gases. [ABSTRACT FROM AUTHOR]

The N–O codoped carbon materials with high specific surface areas and hierarchical porosities were synthesized by a simple dual-templating method using low-cost biomass materials. Toluene was used as a model adsorbate to explore the adsorption performance of all samples, and the sample derived from the greengrocery precursor obtained the highest specific surface area (1650 m2 g−1) and adsorption capacity (627 mg g−1). The experimental results were well fitted by the Langmuir-Freundlich and the Freundlich models, indicating a heterogeneity of the sample surface and a positive adsorption cooperativity. Moreover, the effects of physical structure and surface chemistry on the toluene adsorption performance were also explored. The results showed that the hierarchical porosity and specific surface area were the key factors to physical adsorption, while the presence of nitrogen-containing functional groups could enhance the effect of chemical adsorption significantly and the pyrrolic-N functional groups exhibited the highest affinity with toluene molecules. This study can be used to produce various kinds of low-cost biomass derived heteroatom-doped hierarchically porous carbon adsorbents. The N–O codoped hierarchical carbon materials were synthesized by a simple dual-templating method using diverse biomass materials. Toluene was used as a model adsorbate to explore the adsorption performance of samples. And influence factors of toluene adsorption performance were investigated by experimental data analysis and theoretical simulation. Image 1 • Synthesizing activated carbon materials with low cost and high adsorption ability. • High BET specific area and total volume were obtained. • Obtaining a high toluene adsorption capacity of 627 mg g−1 at 288 K. • The pyrrolic-N functional groups have the highest affinity with toluene molecules. [ABSTRACT FROM AUTHOR]