Search

Reducing carbon emissions remains a formidable challenge under present energy demands and structures. Integrated CO2 capture and utilisation (ICCU) provides a promising pathway for directly capturing and simultaneously utilising CO2 from the diluted exhaust gas. Dry reforming of methane (DRM) can be integrated into the step of catalytic conversion of the captured CO2 with the advantages of utilising two greenhouse gases to yield valuable syngas (CO + H2). The process has great challenges of materials development for efficient performance, in particular under realistic conditions such as the presence of O2 and H2O in the flue gas. This work investigated the ICCU-DRM using simulated flue gases (10 % CO2 + 6.7 % O2 + 6.0 % H2O) in the presence of Ni-CaO dual functional materials, aiming to optimise Ni loading and metal support interaction. It is found that Ni would significantly sinter and further affect the morphologies of CaO adsorbents, resulting in poorer CO2 capture performances. More notably, the Ni was firstly oxidised during CO2 capture and subsequently went through a pre-reduction period in the DRM step. Increased Ni loading decreased the difficulty of activation; however, it derived in more severe carbon deposition. To avert the direct contact of carbon deposition and flue gas, extra carbon steam gasification was introduced, and higher Ni loading contributed to selectively yielding syngas as a by-product. The Ni10- CaO DFM optimally performed 2 conversion and ∼2 H2:CO ratio in the DRM step and ∼75 % CO selectivity in the CSG step at 650 °C. The interaction between Ni and CaO poorly contributes to the performance due to the poor reducibility and accessibility, and the Ni particle size effects only play as spectators in this integrated process.

The investigation of the pyrolysis behaviour of real-world waste plastics (RWWP) and using them as the feedstock to produce carbon nanotubes (CNTs) could serve as an effective solution to address the global waste plastics catastrophe. This research aimed to characterize the pyrolysis behaviour of RWWP via thermogravimetric analysis (TG) and fast pyrolysis-TG/mass spectrometry (Py-TG/MS) analyses. Activation energies (131.04 kJ mol−1 –171.04 kJ mol−1) for RWWP pyrolysis were calculated by three methods: Flynn-Wall-Ozawa (FWO) method, Kissinger-Akahira-Sunose (KAS) method, and Starink method. Py-TG/MS results indicated that the RWWP could be identified as polystyrene (RWWP-1), polyethylene (RWWP-2), polyethylene terephthalate (RWWP-3, 4), and polypropylene (RWWP-5, 6). In addition, RWWP-1, 2, 5, 6 outperform RWWP-3 and 4 as sources of carbon for producing CNTs. The results showed a high carbon yield of 32.21 wt% and a high degree of CNT purity at 93.04%.

Direct air capture (DAC) of CO2 is considered one of the most promising carbon capture methods to reduce ambient CO2 concentration for climate change mitigation. Biochar represents an attractive adsorbent for DAC because it is environmentally friendly and cost-effective. In this work, KOH-activated bamboo biochar shows the CO2 capture capacity of 3.49 mmol g−1 (25 °C, 1 bar), and it is used as an adsorbent to perform direct air capture using a fixed-bed reactor with an ambient CO2 capture capacity of up to 51.74 μmol g−1. Furthermore, the effect of relative humidity on CO2 adsorption by biochar was investigated and exhibited promising stability under 2.7% relative humidity. However, the biochar activity for CO2 capture is reduced to 63.88% under 67.1% humidity after 50 cycles.

Biomass gasification is a promising technology to produce renewable syngas used for energy and chemical applications. However, biomass gasification has challenges of low process energy efficiency, low syngas production with low H2/CO ratio and the sintering of biomass ash which limit the deployment of the technology. This work investigated the influence of in-situ generated heat from CaO–CO2 on cellulose CO2 gasification using a fixed bed reactor, thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR) and differential scanning calorimetry (DSC). Experimental results indicate an approximate 20 °C temperature difference in the fix-bed reactor between cellulose CO2 gasification with the energy compensation of CaO carbonation (denoted auto-thermal biomass gasification) and conventional CO2 gasification of cellulose after the power of external furnaces were turned off. Around 5 times H2/CO molar ratio is obtained after switching off the power in the auto-thermal biomass gasification compared with conventional gasification. The gas yield enhances significantly from 0.29 g g−1 cellulose to 0.56 g g−1 cellulose when CaO/cellulose mass ratio increases from 0 to 5. Furthermore, the TGA-FTIR results demonstrate the feasibility of adopting energy compensation of CaO carbonation to reduce the gasification temperature. DSC analysis also proves that the released heat from the CaO–CO2 reaction reduces the required energy for cellulose degradation.

Recently, photo switching porous materials have been widely reported for low energy costed CO2 capture and release via simply remoted light controlling method. However, most reported photo responsive CO2 adsorbents relied on metal organic framework (MOFs) functionalisation with photochromic moieties, and MOF adsorbents still suffered from chemically and thermally unstable issues. Thus, further metal free and highly stable organic photoresponsive adsorbents are necessary to be developed. CTFs, because of their high porosity and stability, have attracted great attention for CO2 capture. Considering the high CO2 uptake capacity and structural tunability of CTFs, it suggests high potential to fabricate the photoswitching CTF materials by the same functionalisation method as MOFs. Herein, the first series of photo switching CTFs were developed for low energy CO2 capture and release. Apart from that, the CO2 switching efficiency could be doubled either through the azobenzene numbers adjusting method or through the previously reported structural alleviation strategy. Furthermore, the pore size distribution of azobenzene functionalised PCTFs also could be tuned under UV exposure, which may contribute to the UV light induced decrease of CO2 uptake capacity. These photoswitching CTFs represented a new kind of porous polymers for low energy costed CO2 capture.

Thinopyrum intermedium (2n = 6x = 42, StStJrJrJvsJvs), a perennial relative of wheat, is resistant or tolerant to biotic and abiotic stresses, making it an important genetic material for breeding perennial crops. It is also known as intermediate wheatgrass (IWG). The morphological performance, chromosome composition, and yield components of 24 newly developed perennial germplasm, designated 19HSC-Q and 20HSC-Z lines, were investigated from 2019 to 2022. Six lines of 19HSC-Q had higher values of yield component traits, such as thousand-kernel weight, grains per spike, and tiller number than that of Th. intermedium. 19HSC-Q14, 19HSC-Q18 and 19HSC-Q20 had the best agronomic traits with grain number per spike and thousand-kernel weight of 115, 97, and 102 and 7.674, 7.516, and 7.371 g in 2022, respectively. Three 20HSC-Z lines had been growing for two years that the grain number per spike was 116, 88, and 81, and the thousand-kernel weight was 7.146, 6.523, and 5.916 g, respectively. The results of sequential multicolor GISH analysis revealed that the Jvs-subgenome of Th. intermedium were divided into two karyotypes, type-I Jvs with 3 pairs of chromosomes and type-II Jvs with 4 pairs of chromosomes. Both IWG and 24 perennial germplasm had the similar chromosome composition but the translocation between subgenome chromosomes were detected in some lines with prominent comprehensive agronomic traits, such as 19HSC-Q6, 19HSC-Q11, 19HSC-Q18, and 20HSC-Z. The chromosome aberration could be distinguished into two types: the large fragment translocation with Jr-St, Jvs-St, Jr-IIJvs, and Jvs-Jr and the small fragment introgression of St-IJvs. Results of this study provide important materials for the next breeding cycle of cold resistant perennial wheatgrass.

Achieving carbon neutrality is one of the most important tasks to meet the environmental challenges due to excessive CO 2 emissions. Integrated CO 2 capture and utilization (ICCU) represents an effective process for direct utilization of CO 2 -contained exhaust gas (e.g. flue gas), in which converting the captured CO 2 into CO via reverse water–gas shift (RWGS) reaction is a promising route. The dual functional materials (DFMs), containing CO 2 adsorbents and catalysts, are widely applied to achieve ICCU. The conventional active metals (Ni, Fe, etc.)-based DFMs and non-transition metal DFMs (e.g. CaO) are restricted by low CO selectivity, catalytic efficiency or CO generation in the CO 2 capture step. To address the above obstructs in the application of DFMs, the metal oxides-based DFMs, MO x -CaO (M = Al, Ce, Ti or Zr), are synthesized and evaluated. The CeO 2 -CaO outperformed the other metal oxides-based DFMs and possessed significantly improved catalytic performance. It is found that 33% CeO 2 -CaO DFM displayed approximately 49% CO 2 conversion and approximately 100% CO selectivity in integrated CO 2 capture and reverse water–gas shift reaction (ICCU-RWGS) at 650°C, while CaO-alone only achieved approximately 20% CO 2 conversion at the same condition. The surface basicity of CeO 2 is revealed to contribute to the improved catalytic performance by enhancing CO 2 chemisorption and activation in the hydrogenation step. Furthermore, CeO 2 -CaO material possessed excellent cycle stability in 20 cycles ICCU-RWGS, achieving a sustainable and high-efficient performance in CO 2 conversion and CO selectivity.

Pickering emulsions represent an important class of functional materials with potential applications in sustainability and healthcare. Currently, the synthesis of Pickering emulsions relies heavily on the use of strongly adsorbing molecular modifiers to tune the surface chemistry of the nanoparticle constituents. This approach is inconvenient and potentially a dead-end for many applications since the adsorbed modifiers prevent interactions between the functional nanosurface and its surroundings. Here, we demonstrate a general modifier-free approach to construct Pickering emulsions by using a combination of stabilizer particles, which stabilize the emulsion droplet, and a second population of unmodified functional particles that sit alongside the stabilizers at the interface. Freeing Pickering emulsions from chemical modifiers unlocks their potential across a range of applications including plasmonic sensing and interfacial catalysis that have previously been challenging to achieve. More broadly, this strategy provides an approach to the development of surface-accessible nanomaterials with enhanced and/or additional properties from a wide range of nano-building blocks including organic nanocrystals, carbonaceous materials, metals and oxides.

Currently, excessive CO2 emissions have become a global challenge due to their influence on the climate. According to the Paris Agreement, global warming should be limited to 1.5 °C by 2100. Carbon capture and utilisation (CCU) are attractive as they can both reduce CO2 content and utilise CO2 as a carbon resource. However, in conventional CCU processes, CO2 needs first to be extracted and purified for the following utilisation. In contrast, the recently reported Integrated Carbon Capture and Utilisation (ICCU) was designed to realise the overall process in one reactor, where CO2 is captured by adsorbents (e.g., CaO) and utilised in-situ with the introduction of a reducing agent (e.g., H2). This ICCU technology can promote CO2 conversion with fewer intermediate steps, leading to a reduction in overall cost. Energy and economic analysis of ICCU are thus urgently required. According to several recent research, the operational cost of ICCU has been reported to be cheaper than that of CCU. However, a comprehensive view of ICCU is still expected due to further application. This paper focuses on comparing ICCU and conventional CCU processes based on Aspen simulations covering mass balance (i.e., CaCO3 consumption, purge production, annual CO production), energy balance, the total annual cost and the CO cost, etc. Analysis shows that the ICCU process can produce more CO (1.20 Mt year−1), less purge (0.21 Mt year−1), and less consumption of CaCO3 (0.62 Mt year−1) with higher energy efficiency (37.1 %) than the CCU process. The results also show that the total annual cost of ICCU is $867.07 million, corresponding to a total cost of CO of $720.25 per tonne. In contrast, CCU has higher costs, with a total annual cost of $1027.61 million and a total cost of CO of $1004.53 per tonne. The Cost of CO2 Avoided of ICCU (317.11$/ton) is much lower than that CCU (1230.27 $/ton). Therefore, ICCU was confirmed as a better choice for further industrial applications. In addition, H2 is shown to have a significant influence on economic performance, which remains a challenge for further application.

Photo-switching metal–organic frameworks are widely reported for low energy CO2 capture and release. However, owing to the steric hindrance caused by dense packing of MOF solids, the photo-switching efficiency was still severely restricted. Such an issue then further causes low CO2 switching capacity and poor regeneration of MOF adsorbents. Herein, we present a strategy to tailor the photo-switching efficiency of azobenzene functionalized MOFs via a steric hindrance alleviation approach. An azobenzene-containing Zn based MOF, U-mazo, was designed to decrease the steric hindrance of azo benzene pendants in U-pazo (PCN-123). For comparison, two MOFs without azobenzene, IRMOF-3 and CMOF-2, were also fabricated. Results suggested that compared to U-pazo, the cis isomer content in U-mazo increased by 50% upon UV light irradiation at 365 ± 10 nm, which contributed to about 34% enhancement of CO2 switching efficiency. Density functional theory calculations further explained that the optimized switching efficiency of U-mazo resulted from the lower energy cost for trans/cis isomerization of azo benzene pendants. Thereby, a promising strategy for optimizing the switching efficiency of the present photoresponsive MOF is explored and verified, and the structural steric hindrance of photoswitching units plays an important role in isomerization of azobenzene-containing MOFs.

Carbon nanomaterials, such as carbon nanoonions (CNOs), possess promising applications in various fields. There are urgent demands to synthesize carbon nanomaterials from a green and renewable carbon source. In this study, solid CNOs with relatively uniform size distribution (with diameters of about 30–50 nm), abundant structure defects and oxygen-containing surface functional groups (such as –OH and –COOH) are developed from co-pyrolysis of lignin (LG) and polyethylene (PE) in the presence of Ni-based catalysts. The type of catalyst, the concentration of catalyst and catalytic co-pyrolysis temperature play important roles in the morphologies and properties of CNOs as confirmed by TEM and SEM. Furthermore, the produced CNOs can act as a low-cost and highly-efficient adsorbent to remove Cu(II) from aqueous solution according to a homogeneous monolayer, chemical action-dominated, endothermic and spontaneous process. The theoretical maximum adsorption capacity of CNOs calculated from the Langmuir model is 100.00 mg g−1. Surface deposition, complexation, π electron–cation interaction and electrostatic interaction are responsible for the adsorption of Cu(II) using the prepared CNOs.

Carbon nanotube (CNT), has been demonstrated as a promising high-value product from thermal chemical conversion of waste plastics and securing new applications is an important prerequisite for large-scale production of CNT from waste-plastic recycling. In this study, CNT, produced from waste plastic through chemical vapor deposition (pCNT), was applied as a nanofiller in phase change material (PCM), affording pCNT-PCM composites. Compared with pure PCM, the addition of 5.0 wt% pCNT rendered the peak melting temperature increase by 1.3 ℃, latent heat retain by 90.7%, and thermal conductivity increase by 104%. The results of morphological analysis and leakage testing confirmed that pCNT has similar PCM encapsulation performance and shape stability to those of commercial CNT. The formation of uniform pCNT cluster networks allowed for a large CNT loading into the PCM on the premise of free phase change, responsible for the high thermal conductivity inside the homogeneous phase. Thus, the resulting capillary forces retained a high latent heat capacity and suitable melting temperature and prohibited PCM leakage from the matrix to the outside during re-melting as the pCNT loading ratio increased. Therefore, the as-prepared pCNT-PCM composite is believed to have similar potential to cCNT and shows prominent performance as a flowable conductive filler for battery thermal management systems.

Carbon dioxide (CO2) capture is critical for emission reduction. Biochar is a promising adsorbent for CO2 capture. In this work, the effect of relative humidity and biochar activation with steam or KOH treatment on CO2 capture was investigated. The results demonstrate that the biochar sample activated by KOH has a high CO2 capture capacity (50.73 mg g−1). In addition, the biochar after 1.0 h of steam treatment showed a carbon capture capacity of 38.84 mg g−1. The results also show that the capture ability of biochar decreased as CO2 concentration decreased from 100% to 15%. The relative humidity had a negative impact on CO2 capture over biochar. The CO2 capture capability of biochar materials treated by steam decreased by a range of 31.38%–62.89% as the relative humidity rose from 8.8% to 87.9%. Furthermore, the lifetime of biochar samples at various relative humidity shows that increased relative humidity had a negative impact on CO2 adsorption due to water molecules occupying active sites.

Producing carbon nanotubes (CNTs) from waste plastics could enhance the economic feasibility of the waste management process. Spray pyrolysis is a practical and promising method in this research area. However, the synthesis of CNTs by a spray pyrolysis method is highly reliant on a variety of parameters. Therefore, parameters, including the amount of waste plastics (polypropylene), the catalyst feeding rate and the concentration of the catalyst, and the reaction temperature, were investigated in this work. Results indicate that the reaction factors can influence the carbon deposition and carbon nanotubes yield (CNTs yield). The formed catalyst size played a significant role in the synthesis process. The carbon deposition and CNTs yield reached the top at 21.11 mg g−1plastic and 11.60 mg g−1plastic, respectively, when the PP amount is 2.0 g, the feeding rate of catalyst is 9.0 mL h−1, the concentration of catalyst is 0.2 mol L−1, and the reaction temperature is 800 °C in this work.

Calcium looping is considered to be one of the best approaches for industrial CO2 high-temperature capture, whereas current CaO-based sorbent suffers poor cyclic performance, especially the relations between precursor structure and CO2 fast adsorption capacity still need to be further revealed. In this work, three calcium-based metal frameworks (Ca-MOFs) with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. It was found that LAC MOF-derived CaO achieved a fast adsorption capacity of 11.8 mmol g−1 (78 % of total adsorption) after 4 cycles. This was because the fiber bundle-like original LAC MOF structure changed gradually to nanosheets after 600 °C pyrolysis and finally formed regular CaO spheres with an average size of 100 nm after an 800 °C -calcination, thereby preventing further aggregation of CaO particles during the thermal transition process. In addition, the adsorption performance did not rely on pore structure, and thus pore-blocking showed little influence on the performance of CO2 capture. Hence, high stability can be achieved simply by avoiding particle sintering. The systematic study marks the significance of precise tailoring of nano-CaO for achieving the desired performance of CO2 fast adsorption.

Food waste generated from the food service sector is associated with significant social, ecological and economic impacts. There is lack of knowledge on status quo, drives and solutions for food waste in food service sector despite its importance. In order to understand and identify key issues of food waste and find potential solutions for food waste minimization in food service business, both a questionnaire and a qualitative study were conducted using China as a case country. 228 questionnaires were collected and in a subsequent workshop 51 representatives from 19 enterprises and other organizations joined. The results show that more than half (57%) of the respondents pay no attention to food waste issue, while majority of the respondents (86%) pay attention to regulations and policy on waste issues, suggesting that these instruments would be efficient tools to take actions on reducing food waste. The workshop identified 21 drivers with division of different stages including pre-kitchen (upstream processing, procurement and storage), kitchen and post-kitchen (consumption & communication with consumers), which is then categorized according to the focus (including 13 internal drivers derived from foods service business itself and 8 external factors caused by other parties). 33 possible solutions were proposed for food waste mitigation and reduction, among which 25 were directly for Chinese food service business internal improvement such as food waste management system upgrading, staff capacity raising, innovative actions, more tasteful dishes and adjusted potion size from different angles or for the joint activities by food service business and other relevant stakeholders like consumers interaction, clear communicated procurement standards with upstream suppliers. This paper pinpointed some interesting findings under the Chinese context, such as lacking of food waste measurement, considerable amount of upstream processing waste resulted from combination of unclear standards and buyers’ privilege”, noticeable food waste from central kitchen and decoration/free snacks food waste etc.. This paper has not only identified the current status quo of the Chinese food service business food waste, but also summarized systematically the potential drivers from the business with specific division of different stages and gave out possible solutions, all directly from the staffs’ opinions. The findings would be referential to global food waste issues under similar situation.

This study presents a novel combination of microwave irradiation and structured zeolite/SiC foam catalyst to improve the methanol-to-hydrocarbons (MTH) process as well as its environmental sustainability. Accordingly, ZSM-5/SiC foam was studied under microwave irradiation at various reaction temperatures (400–550 °C) and space velocities (8 and 12 h−1) and compared to conventional ZSM-5 pellets. ZSM-5/SiC foam promoted higher selectivity towards C1−C5 hydrocarbons (∼95%) and particularly propylene (∼40% at 400 °C and 8 h−1) compared to ZSM-5 pellets (∼40% and 6–9%, respectively) due to the enhanced mass and heat transfers. The microwave-assisted MTH process with both the structured catalyst and pellets was also assessed on the environmental sustainability via life cycle assessment in comparison with the conventionally-heat process with the structured catalyst. The results showed that the microwave-based process with the structured catalyst could reduce the environmental impacts of propylene production by 22–30% compared to the conventionally-heated process with the same catalyst.

Integrated carbon capture and utilization (ICCU) presents an ideal solution to address anthropogenic carbon dioxide (CO 2) emissions from industry and energy sectors, facilitating CO 2 capture and subsequent utilization through conversion into high-value chemicals, as opposed to current release into the atmosphere. Herein, we report the synergistic coupling of porous CaO, as a sorbent for CO 2 capture, and Ni doped CeO 2 nanorods, as catalytic sites for CO 2 reduction. It is found that ceria is shown to possess the capacity for CO 2 utilization, however, critically it only results in the generation of CO due to the weak CO-ceria bonding. The addition of Ni active sites gives rise to CH 4 being the predominant product, via the strong interaction between Ni species and CO, which facilitates further reduction. Through tuning Ni loadings, we have evaluated the role of catalytic active site size, with a Ni loading of only 0.5 wt% providing optimal performance through the formation of sub-nanometer sized clusters. This near-atomic active site dispersion gives rise to CH 4 productivity and selectivity of 1540 mmol g −1 Ni and 85.8%, respectively, with this optimal combination of catalyst and sorbent demonstrating high stability over 10 cycles of ICCU process. These observations in parallel with the synergistic coupling of earth-abundant, low-cost materials (CaO and Ni) will have broad implications on the design and implementation of high efficiency, cost-effective ICCU materials and processes.

Integrated CO2 capture and methanation (ICCM) is attracting more attention to promote the reduction of CO2 emission. This work developed and applied a set of combined materials using Ru/CeO2 as catalyst and physically mixed Li, Na, K-doped MgO as adsorbent for the ICCM process. The influences of morphologies of CeO2 (rod, particle, and cube) in combined materials are investigated explicitly in terms of CO2 conversion and CH4 yield. Compared to the CeO2 with cube morphology, the CeO2 with rod and particle morphologies showed better Ru dispersion and more abundant support-metal interaction (SMI). The combined materials with rod and particle morphologies CeO2 (Ru/rod-CeO2-MgO and Ru/particle-CeO2-MgO) show more superior catalytic performance (0.33 and 0.29 mmol/g for CH4 yield and 55.7% and 59.8% for CO2 conversion, respectively) than that with Ru/cube-CeO2-MgO. Furthermore, the Ru/rod-CeO2-MgO shows excellent catalytic stability and reusability during 9 cyclic ICCM evaluations. In situ DRIFTS of Ru/CeO2-MgO revealed that the formates and dissociated CO2 (Ru-CO) might be the critical methanation intermediates in ICCM.

Thermo-chemical conversion of plastics provides an economic flexible and environmentally friendly method to recycle waste plastics, and generates valuable materials, such as carbon nanotubes (CNTs) and syngas. The development of catalysts is a key challenge for improving the quantity and quality of CNTs. In this study, spherical catalysts loaded with Ni were studied to control CNTs growth using waste plastic as the feedstock. Three parameters were studied, including catalytic temperature, Ni content and plastics/catalysts ratio. A fixed two-stage reactor was used for thermal pyrolysis of plastic waste and the materials were characterized with various methods including scanning electronic microscopy (SEM), temperature programme oxidation (TPO) and X-ray diffraction (XRD). The results showed that different contents of Ni loaded on sphere results in the formation of metal particles with various sizes, thus leading to CNTs production with different quantity and quality. In addition, an optimal catalytic temperature at 800 °C is suggested for CNTs formation with the Ni/sphere catalyst, as the catalyst might not be activated at 600 °C and 700 °C.

In the present study, the coked catalysts derived from catalytic reforming of the pyrolysis volatiles of polyethylene (PE), lignin (LG) and their mixture were developed as low-cost and environmentally-friendly carbon materials-containing composites to remove heavy metal ions from aqueous solution. The composites were thoroughly characterized by SEM, TEM, XRD, TGA and FT-IR and then their adsorption capability towards Pb(ii) was investigated. It is found that curved cone-shape carbon nanotubes (CNTs) with abundant structural defects and O-containing surface functional groups, such as C-O, CO and -OH, can be obtained from the catalytic reforming of the mixture of PE and LG. The CNT-containing catalyst composite presents a superior adsorption capability towards Pb(ii) when it is employed in Pb(ii) removal. Adsorption isotherm and adsorption kinetics studies show that the adsorption process can be well simulated by the Langmuir isotherm and pseudo-second-order model, demonstrating that the adsorption is subjected to a homogeneous and chemical process. The calculated maximum adsorption capacity is as high as 146.08 mg g-1, which is much higher than most of the adsorbents reported. Moreover, thermodynamic analysis reveals that the adsorption is spontaneous and endothermic. Accordingly, the used catalyst from the catalytic reforming can be developed as a low-cost and highly-efficient adsorbent.

Perovskites are good candidates as a catalyst support to enhance the catalytic performance of Ni catalysts in steam methane reforming for hydrogen production. To obtain a Ni/perovskite catalyst with a high activity and stability, different LaBO3 (B = Al, Fe, Mn), La0.7A0.3AlO3−δ (A = Ca, Ba, Ce, Zn, Sr, Mg) and La1−xMgxAlO3−δ perovskites were prepared and their role in supporting Ni catalysts was comprehensively investigated in the current work. Catalyst characterization methods, including XRD, H2-TPR, H2-TPD, XPS, TG and Raman spectroscopy, were also used to understand the underlying mechanisms. The results show that the doping of Ca, Ba, Ce and Zn in the A site of the perovskite lowers the catalytic activity, while the partial substitution of Mg and Sr could improve the activity of Ni/LaAlO3. More importantly, it is suggested that the Ni/La0.7Mg0.3AlO3−δ catalyst has an outstanding catalytic activity and resistance to carbon deposition, and there is some carbon deposited after a stability test lasting for 35 h. The excellent catalytic performance is determined to be due to the higher dispersion of active Ni, the greater the amount of surface oxygen, the stronger the interaction between the active metal and support due to the partial doping of Mg.

Thermo-chemical conversion of carbonaceous wastes such as tyres, plastics, biomass and crude glycerol is a promising technology compared to traditional waste treatment options (e.g. incineration and landfill). The process promotes the sustainable management of carbonaceous wastes and realizes the potential value of these wastes. Carbon nanotubes (CNTs) are one of the most extensively investigated and high-value materials due to their featured electrical, mechanical and physical properties. Producing CNTs from waste materials could solve the issues of waste management and simultaneously bring down the cost of CNT production. This review focuses on the four most abundant waste carbonaceous materials (waste tyres, plastics, biomass and crude glycerol) which have great potential to be alternative feedstocks for CNT production. The review considers the background of these four major types of waste to highlight the incentives in using thermo-chemical conversion to deal with these waste materials. Catalyst development for thermo-chemical conversion is discussed to summarize the most common catalysts and provide guidance for future novel catalyst improvement. Current research studies regarding CNT and hydrogen production from waste materials have been reviewed which show that the topic is highly attractive for researchers. The applications of CNTs have also been grouped based on different properties, aiming to guide the future research to explore the potential applications of CNTs synthesized from wastes. This review provides an overview of the recent developments in this research area and stimulates research to promote the deployment of the technology.

Carbon capture and sequestration technologies are essential to reduce CO2 emissions which are responsible for global warming. Carbon-based materials can play an important role in the reduction of CO2 emissions. These materials are normally produced from biomass through technologies such as pyrolysis and hydrothermal carbonization. The type of biomass feedstock and biomass conversion conditions can significantly affect the textual properties and surface chemistry of the carbon materials. Various modification methods such as material activation or N-doping can improve the properties of carbon materials to obtain better CO2 capture effects. This review summarizes recently reported research in the areas of using biomass-based materials for CO2 capture. The technologies of biomass conversion to carbon materials and modification of the carbon materials are critically analyzed. Meanwhile, the mechanisms of the CO2 capture process and research of different modification carbon materials for CO2 capture are also discussed. Finally, potential future research directions are suggested to promote carbon capture using biomass-based materials.

This study reports a set of new vapor liquid equilibrium (VLE) data for the binary mixture of 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) at temperatures from 253.15 to 303.15 K, and the saturated vapor pressures of R290 and R134a at temperatures ranging from 253.15 to 323.15 K using a recirculation apparatus with view windows. The VLE data were correlated with the well-known NRTL-RK, Wilson-RK, and UNIQ-RK models. The results indicated that all the models showed good agreement with the experimental data. The average absolute relative deviations of pressure (AARDp) were between 0.01% and 0.02%, while the average absolute deviations of vapor phase mole fraction (AADy) were between 0.0035 and 0.0041. Positive azeotropic behavior could be observed for the R134a + R290 system, and the azeotropic point data at six temperatures from 253.15 to 303.15 K were presented.

Carbon quantum dots (CQDs), as a novel fluorescent carbon nanomaterial, have raised worldwide concern on account of their remarkable biocompatibility, water solubility, chemical stability, nontoxic...

It is widely acknowledged that the increasing CO2 concentration has led to the rise of temperature in the earth. Thus, capturing CO2 to alleviate environmental catastrophic is becoming important and urgent. Among the CO2 sorbents reported, solid adsorbents are advantageous in CO2 adsorption, CO2/N2 selectivity, easy operation and good regeneration ability. Biochar-based sorbents are promising for CO2 capture because they are self-sufficient in energy requirements, wide availability, renewability, low cost, and high porous structure. In addition, N-containing functional groups are used to improve the capability of CO2 adsorption of biochar. This review aims to evaluate the preparation and performance of nitrogen-enriched biochar for CO2 capture. Throughout this review paper, the current N-containing precursors and biomass, as well as the technologies for the preparation of N-rich biochar are discussed. It is concluded that cheaper and more sustainable ways should be proceeded to produce N-rich biochar in the field of CO2 capture research.

Carbon nanotubes (CNTs) are promising nanofillers to enhance the mechanical performance of polymers. Through catalytic conversion, waste plastics can be converted into CNTs, which could be an alternative to commercial CNTs (cCNTs). Exploring a practical application of waste-plastic-derived CNTs will largely promote the technology development related to waste plastic management and CNT production. In this work, CNTs produced from plastics, named pCNTs, were applied as fillers to epoxy resin (EP), while commercial CNTs (cCNTs) were used as a reference. The carboxyl groups were effectively inserted on the CNT skeleton by a facile purification and modification. After ultrasonic dispersion, the modified pCNTs (M-pCNTs) were uniformly dispersed and loaded in the EP matrix. Better mechanical properties than EP were attained with a Young's modulus of 3776.9 MPa, a tensile strength of 37.3 MPa, a fracture strain of 6.32%, and a fracture strength of 111.7 MPa with 2 wt % M-pCNT loading. Thus, pCNTs enhanced the toughness of the EP composites and simultaneously retained the stiffness. It was suggested that CNT pull-out and bridging were predominant toughening mechanisms for pCNT/EP composites. Notably, the coated film developed between residual metal in M-pCNTs and EP built a strong interfacial interaction and reinforced the EP composites.

Ni-modified ZSM-5 catalysts are prepared by a one-pot hydrothermal synthesis method and applied to the steam reforming of naphthalene as a tar model compound. The effects of the reaction temperature, silica-alumina ratio (Si/Al) and metal content on the catalytic performance for reforming naphthalene are investigated. Characterization results indicate that the Ni-modified ZSM-5 catalysts maintain the original MFI structure of ZSM-5 and a portion of Ni is successfully introduced into the zeolite structure. When the reaction temperature is 800 °C, the conversion efficiency of naphthalene achieves 91.5% with a high yield (6.75%) of hydrogen. Zeolite catalysts with higher Si/Al ratios improve the conversion of naphthalene to syngas, demonstrating their better catalytic activity. An appropriate active metal content (2.4 wt%) contributes to the catalytic performance of the catalyst owing to the strong metal-support interaction, resulting in resistance to sintering and carbon deposition. The reaction mechanism involved in the catalytic reforming of naphthalene is proposed. The application of a novel one-pot hydrothermal synthesis method greatly promoted the catalytic activity of Ni@ZSM-5, which provided an appropriate and universal approach for the improvement and optimization of tar reforming catalysts.