Carbon Yield Research Articles

Dicationic ionic liquid‐grafted UiO‐66 as efficient catalyst for CO2 conversion into cyclocarbonate under cocatalyst‐free and solventless conditions

CO2 chemical fixation offers a feasible approach for carbon mitigation and high‐value utilization, but it is still challenging to develop an efficient catalyst for CO2 conversion into cyclic carbonate. Herein, the triethylenediamine‐derived dicationic ionic liquids (DIL‐X, X = Cl, Br, and I) were grafted into UiO‐66 linkers through self‐assembly of Zr4+ ions and the mixed ligands of terephthalic acid and DIL‐bearing dicarboxylic acid, resulting in UiO‐66‐DIL‐Xn, (n designated as molar amount of the feeding DIL‐X). Their catalytic performance was evaluated by the epoxide cycloaddition reaction in the absence of solvent and cocatalyst. Among them, the UiO‐66‐DIL‐Cl0.4 catalyst exhibited outstanding performance, with a chloropropene carbonate yield of 92% and a high selectivity of 99% under 0.1 MPa CO2 at 110 °C for 16 h. Its high activity could be ascribed to the cooperativity among Lewis acidity of MOF nodes, the enhanced CO2 absorption, and the strong nucleophilicity offered by halogen ions of ionic liquid‐modified MOF. Moreover, UiO‐66‐DIL‐Cl0.4 presented excellent recyclability and substrate extension. A potential catalytic mechanism for the epoxide‐CO2 cycloaddition into cyclic carbonate has been proposed. This work will shed light on the rational design of functionalized MOFs‐based catalysts for CO₂ utilization.

Influence of varying aluminum-based combustion compartment sizes on groundnut shell biochar properties

The process variables during biochar production play a crucial role in determining its properties. Factors like temperature, heating rate, reactor configuration, and residence time can significantly impact biochar quality. The aim of this study is to determine the impact of reactor configuration on the yield and properties of groundnut shell biochar. For this investigation, the volumes of aluminum-based combustion compartments in a biomass-fueled TLUD biomass gasifier were varied, and the resulting biochar was analyzed using SEM, EDX, and FTIR. It was observed that the increase in the combustion chamber of the gasifier led to an increase in the amount of biomass fuel utilized in the system, which led to an increased reactor’s temperature and varied carbonization duration and yield. Elemental composition showed that an increase in reactor volume led to an increase in biochar carbon content and reduced silica content. The SEM analysis confirmed that decreasing the combustion compartment sizes increased porosity and roughness, as well as visible fissures and crevices on the biochar surface. FTIR analysis revealed similarities in functional groups, with many peaks appearing at higher wavenumbers as the combustion compartment sizes decreased. This study innovatively examines how varying aluminum-based combustion compartment sizes and biofuel mass affect groundnut shell biochar properties using a TLUD gasifier, emphasizing its significance for optimizing biochar production and advancing sustainable practices.

Turbostratic carbon nanofibers produced from C2HCl3 over self-dispersing Ni-catalyst doped with W and Mo

In this research, a self-dispersing 92Ni-4Mo-4W catalyst showing high productivity towards the H2-assisted synthesis of turbostratic carbon nanofibers was proposed. The effect of reaction temperature on the efficiency of 92Ni-4Mo-4W alloy in the decomposition of trichloroethylene was studied. It was found that in the temperature range of 580–620 °C, the most rapid destruction of the initial alloy followed by the growth of carbon material is realized. This is confirmed by the minimum induction period (9–11 min) and the maximum carbon yield (95–107 g/gcat). As revealed, the catalytically active particles of submicron size contain uniformly distributed Ni, Mo, and W. It is demonstrated that the decomposition of trichloroethylene over the 92Ni-4Mo-4W catalyst results in the formation of a turbostratic carbon material with a segmented structure, containing a minimum quantity of amorphous carbon and possessing high textural characteristics (specific surface area of 330–410 m2/g; pore volume of 0.48–0.58 cm3/g).

Oxidative Upcycling of Polyethylene to Long Chain Diacid over Co-MCM-41 Catalyst.

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high-value and high-volume saturated dicarboxylic acids in high carbon yield of 85.9 % in which the carbon yield of long chain dicarboxylic (C10-C20) acids can reach 58.9% over cobalt-doped MCM-41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short-chain (C4-C10) to long-chain ones (C10-C20) through changing cobalt loading of MCM-41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one-step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids.

Oxidative Upcycling of Polyethylene to Long Chain Diacid over Co‐MCM‐41 Catalyst

AbstractPlastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high‐value and high‐volume saturated dicarboxylic acids in high carbon yield of 85.9 % in which the carbon yield of long chain dicarboxylic (C10‐C20) acids can reach 58.9% over cobalt‐doped MCM‐41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short‐chain (C4‐C10) to long‐chain ones (C10‐C20) through changing cobalt loading of MCM‐41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one‐step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids.

Balancing Greenhouse Gas Emissions and Yield through Rotational Tillage in the Cold Rice-Growing Region

Tillage practices are of critical importance in maintaining soil quality on cropland and for food production, with rice cultivation representing a significant portion of the world’s food production and greenhouse gas (GHG) emissions. While numerous studies have examined the effects of reduced and no-tillage on soil GHG emissions and rice yields, the impact of adopting a rotational approach to tillage practices on the rice cultivation cycle remains uncertain. In this study, we conducted a four-year (2017–2020) field experiment in a single rice-growing area in Northeast China with the aim of investigating the effects of different tillage practices on GHG emissions from paddy fields and rice yields under full straw return conditions. We set up three experimental treatments: rotary tillage, plowing, and rotational tillage (i.e., a combination of one year of plowing and one year of rotary tillage). The results showed that averaged across all treatments, average methane (CH4, 302.6 ± 51.1 kg ha−1) and nitrous oxide (N2O, 0.86 ± 0.361 kg ha−1) emissions and rice yield (9.0 ± 0.9 t ha−1) did not exhibit significant inter-annual variability during the entire experimental period and were comparable to the average for the region. The ranking of GHG emissions during the rice-growing season was as follows: rotary tillage > plowing > rotational tillage. Across the experimental period, CH4 and N2O emissions were 9.1% and 8.5% lower in the plowing treatment and 21.2% and 13.1% lower in the rotational tillage treatment compared to the rotary tillage treatment. During the experimental period, there was no significant effect of tillage treatments on rice yield. This reduction in emissions may be attributed to changes in soil penetration resistance. In the rotational and plowing treatments, soil penetration resistance was in a range more adapted to rice growth and GHG emissions reduction compared to the rotary tillage treatment. The yield-scale GHG emission intensity was reduced by 12.7% and 26.1% in the plowing and rotational tillage treatments, respectively, in comparison to the rotary tillage treatment. This suggests that rotational tillage is a management practice that can achieve greenhouse gas emission reductions in paddy fields and stabilize or possibly increase rice yields. Consequently, the results demonstrated that a rotational alternation of multiple tillage practices is a synergistic strategy for achieving low carbon and high yield in rice in the cold rice-growing region of Northeast China.

Preparation of Schiff base metal catalyst and its catalytic synthesis of propylene carbonate from CO2

In recent years, research on the conversion of CO2 into fine chemical products has emerged as a prominent and dynamic area of study. In this study, four ligands were synthesized using salicylaldehyde, o-phenylenediamine, ethylenediamine, hexanediamine, and 2,6-diaminopyridine as precursors. Subsequently, these ligands were reacted with cobalt nitrate, zinc chloride, and aluminum chloride to synthesize 12 Schiff base metal complexes, which were employed as catalysts for the synthesis of propylene carbonate from CO2 and epichlorohydrin. The findings reveal that the SF-L/Co catalyst demonstrated superior performance, potentially attributed to the robust chelating capability of Co, leading to the provision of more acidic metal centers. Characterization of SF-L/Co was conducted utilizing scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Process conditions were optimized, resulting in the achievement of a 100% yield and selectivity of propylene carbonate under optimal reaction conditions, without the generation of any by-products. Furthermore, the catalyst exhibited remarkable reusability, demonstrating consistent catalytic activity over five successive cycles without a substantial decrease in performance.

Celecoxib Catalyzed the Coupling Reaction of Epoxide and CO2

Abstract: In this study, high yields of various cyclic carbonates are obtained by employing the drug celecoxib to promote the coupling reaction of CO2 and epoxide using tetrabutylammonium bromide. This strategy enables the synthesis of benzoic acid, phenylpropiolic acid, and 2, 4- quinazolinedione. In addition, the model reaction mechanism is proposed.

A synergistic approach for lignin biofuel production: Integrating non-catalytic solvolysis with catalytic product upgrading

Enzymatic hydrolysis lignin (EHL) is a large-scale industrial waste generated from the bio-ethanol production process. Its complex and heterogeneous nature as well as its low solubility in common solvents, has posed a persistent barrier to its effective utilization. Here, EHL was converted into biofuel through a two-step process, involving non-catalytic solvolysis followed by catalytic product upgrading. The non-catalytic solvolysis step achieved complete EHL liquefaction in a mixture of isopropanol and H2O without char formation. In this step, H2O disrupts the hydrogen bonds in EHL and isopropanol break π-π stacking interactions between the aromatic rings in EHL·H2O also enhances EHL depolymerization, while isopropanol, as a hydrogen donor solvent, provides hydrogen that stabilizes active intermediates. In the catalytic product upgrading step, the liquid product of the first step was transformed into biofuels rich in cycloalkanes, arenes and alkylphenols, with a total carbon yield of 45.6 %. Isopropanol-H2O reforming reactions provided hydrogen for the upgrading process, avoiding the introduction of H2. This work demonstrates an effective approach for converting EHL into biofuels.

Reducing Ammonia (NH3) Levels in Fish Cage Water Using Activated Carbon Adsorbent Derived from Purple Corn Cob

Successfully made adsorbent of activated carbon made from purple corn cob which aims to minimize ammonia (NH3) levels found in water in fish farming with cage ponds. Activated carbon using carbonization method with a change in temperature that is between 550°C, 600°C, and 650°C and activation using Na2CO3 solution as activator. Activated carbon that has been obtained has exceeded the standard of SNI No.06-3730-1995, with characteristics including carbon yield ranging from 79.71% to 89.85%, moisture content ranging from 11.3% to 25.4%, volatile matter content ranging from 10.10% to 24.5%, ash content ranging from 9.7% to 9.9%, and fixed carbon content ranging from 65.7% to 79.7%. Then test results were obtained such as CO2 functional groups were found to enhance the adsorption process. Activated carbon displays the presence of a predominantly amorphous structure but also revealed a crystalline carbon structure. The highest peak was obtained at 29.7° with Miller index (201). The activated carbon displays the presence of pores on the scattered surface with carbon elements dominating. Adsorption mechanism to reduce ammonia (NH3) using activated carbon due to intermolecular interaction process. So that when testing the application for ammonia absorption, the best results were obtained in the sample with an adsorbent mass of 1.50 g at a carbonization temperature of 650°C with an adsorption capacity value of 546.34 mg/g and ammonia reduction of 82%. This research can open up opportunities for the potential development of new materials, especially for fish farming through cage techniques.

Creation of a NADH-dependent meso‑diaminopimelate dehydrogenase by site-saturation mutagenesis for producing L-lysine in Corynebacterium glutamicum

The meso‑diaminopimelate dehydrogenase (DapDH) is crucial for efficiently biosynthesizing L-lysine. In this study, a NADH-dependent DapDH was created and was used to increase L-lysine production in Corynebacterium glutamicum. To do this, the critical amino acid residues for switching cofactor preference in DapDH from C. glutamicum (CgDapDH) were investigated by bioinformatics analysis and alanine-scanning mutagenesis and indicated that three residues (Tyr11, Arg36 and Arg37) showed the critical roles in changing the cofactor preference. Subsequently, these residues were mutated by site-saturation mutagenesis and indicated that variants CgDapDHY11K, CgDapDHR36E and CgDapDHR37E showed an increased activity using NAD+ as cofactor. Moreover, the best variant CgDapDHY11K/R36E with enhanced affinity for NAD+ (Km = 2.3 ± 0.3 mM) and specific activity (406 ± 28 mU/(mg protein)) was obtained after combinatorial mutagenesis. The results of L-lysine fermentation showed that the resultant strain XQ-7 with overexpression of CgDapDHY11K/R36E increased the final titer (from 186.7 ± 5.6 g/L at 72 h to 191.5 ± 10.7 g/L at 60 h), carbon yield (from 0.53 g/(g glucose) to 0.61 g/(g glucose)) and average space-time yield (from 2.59 g/(L∙h) to 3.19 g/(L∙h)) compared with the original strain XQ-6 in fed-batch fermentation. This is the first report of an artificial NADH-dependent CgDapDH that increases L-lysine production because of decreasing the requirement of NADPH.

Metal-Catalyzed Thermo-Catalytic Decomposition and Continuous Catalyst Generation

In this study, metal dusting is utilized to initiate a two-stage thermo-catalytic decomposition (TCD) process. Stage 1 starts with metal-catalyzed TCD, and in stage 2 the metal-catalyzed carbon catalyzes additional TCD. TEM is presented of the early- versus late-stage TCD to qualitatively illustrate the second-stage TCD by the metal-catalyzed carbons. Corresponding SEM illustrates differences in growth type and surface density between early versus late reaction times, with backscattered imaging differentiating the first- versus second-stage TCD. TGA supports the microscopic inference of a second carbon phase by the presence of an early (low-temperature) reaction peak, characteristic of low-structure or disordered carbon as the second-stage TCD carbon. Raman analysis confirms that the second-stage carbon deposit is more disordered and unstructured, especially at 1000 °C, supported by the ID/IG and La value changes from 0.068 to 0.936 and 65 nm to 4.7 nm, respectively. To further confirm second-stage TCD occurrence upon pre-catalyzed carbons, two carbon blacks are tested. Exposing a combination of edge and basal or exclusively basal sites for the graphitized form, they afford a direct comparison of TCD carbon nanostructure dependence upon the initial carbon catalyst nanostructure. Pre-oxidation of the stainless-steel wool (SSW) prior to TCD is advantageous, accelerating TCD rates and increasing carbon yield relative to the nascent SSW for an equivalent reaction duration.

Co-pyrolysis of algae and lignocellulosic biomass in molten salts to produce N-doped carbon for supercapacitor application

Conventional pyrolysis strategies present challenges in maintaining the nitrogen fraction and improving the electrical conductivity of the product carbon at the same time. Co-pyrolysis of algae and lignocellulosic biomass with different temperature-controlled procedures in molten Na2CO3–K2CO3 is innovatively proposed to produce N-doped capacitive carbon. Results show that interactions between algae and bamboo in the presence of molten salt incorporate more nitrogen species into the carbon matrix and increase carbon yield. Co-pyrolysis with an optimal switching temperature of two-stage pyrolysis improves the nitrogen amount in carbon and the carbon yield by up to 108.7 % and 34.7 %, respectively. Through diffusion and infiltration, the liquid molten carbonates increase the contact area between the salt molecules and the carbon matrix, resulting in superior and uniform capacitive carbon. The resulting carbon shows a high specific capacitance of 306.2 F/g at 0.25 A/g with a cycling stability of 91.3 % after 5000 cycles, due to its hierarchical porous structure, high specific surface area (1326.58 m2/g) and abundant pyridine-N/pyrrolidine-N (81 %). Therefore, applying co-pyrolysis in molten carbonates with two-stage pyrolysis to produce high-yield N-doped carbon for supercapacitor application is proved to be promising.

Carbonization of bacterial cellulose with structure retention and Nitrogen/Sulfur/Oxygen doping for application in supercapacitors electrode

Bacterial cellulose (BC) presents great potential as an economical and sustainable biomass for the preparation of porous carbon electrodes for electrochemical energy storage. However, it is a challenge to maintain the natural structural advantages of BC and regulate the chemistry during the carbonization, significantly hindering the practical application. This study proposes a straightforward and efficient approach to rationally control the carbonization process of BC for improving structure retention and endowing multiple atomic doping, contributing an advanced electrode for supercapacitors. The addition of ammonium sulfate ((NH4)2SO4) is instrumental in promoting the early dehydration carbonization, forming a carbon layer with thermal insulation. This thermal barrier suppresses the volatile organic compound formation, resulting in the inhibition of volume shrinkage and boosted carbon yield. Moreover, the air activation combined with the addition of (NH4)2SO4 contributes to a Nitrogen/Sulfur/Oxygen-doped carbon electrode. The well-maintained hollow structure and diverse chemistry provide sufficient active sites and enhanced ion diffusion, resulting in a specific capacitance of 268.2 F/g at a current of 0.5 A/g and outstanding capacitance retention of 99.46 % after 10,000 cycles at 5 A/g. This work provides a deep insight into the development of cost-effective biomass in developing advanced carbon electrodes for efficient energy storage.

Demineralization activating highly-disordered lignite-derived hard carbon for fast sodium storage

Lignite, as one of the coal materials, has been considered a promising precursor for hard carbon anodes in sodium-ion batteries (SIBs) owing to its low cost and high carbon yield. Nevertheless, hard carbon directly derived from lignite pyrolysis typically exhibits highly ordered microstructure with narrow interlayer spacing and relatively unreactive interfacial properties, owing to the abundance of polycyclic aromatic hydrocarbons and inert aromatic rings within its molecular composition. Herein, an innovative demineralization activating strategy is established to simultaneously modulate the interfacial properties and the microstructure of lignite-derived carbon for the development of high-performance SIBs. Demineralization process not only creates numerous void spaces in the matrix of lignite precursor to assist aromatic hydrocarbon rearrangement, thereby reducing the ordering and expanding interlayer spacing, but also exposes more interfacial oxygen-containing functional groups to effectively increasing the sodium storage active sites. As a result, the optimal demineralized lignite-derived hard carbon (DLHC 1300) delivers a high reversible capacity of 335.6 mAh g−1 at 30 mA g−1, superior rate performance of 246.3 mAh g−1 at 6 A g−1 and nearly 100 % capacity retention after 1100 cycles at 1A g−1. Furthermore, the optimized DLHC 1300 material functions as an outstanding anode in sodium ion full cells. This work significantly advances the development of low-cost, high-performance commercial hard carbon anodes for SIBs.

Sorption of Iodine on Biochar Derived from the Processing of Urban Sludge and Garden Waste at Different Pyrolysis Temperatures.

The United Nations proposed the Sustainable Development Goals with the aim to make human settlements in cities resilient and sustainable. The excessive discharge of urban waste including sludge and garden waste can pollute groundwater and lead to the emission of greenhouse gases (e.g., CH4). The proper recycling of urban waste is essential for responsible consumption and production, reducing environmental pollution and addressing climate change issues. This study aimed to prepare biochar with high adsorption amounts of iodine using urban sludge and peach wood from garden waste. The study was conducted to examine the variations in the mass ratio between urban sludge and peach wood (2/1, 1/1, and 1/2) as well as pyrolysis temperatures (300 °C, 500 °C, and 700 °C) on the carbon yield and adsorption capacities of biochar. Scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectrometry, powder X-ray diffraction, and elemental analysis were used to characterize the biochar produced at different pyrolysis temperatures and mass ratios. The results indicate that the carbon yield of biochar was found to be the highest (>60%) at a pyrolysis temperature of 300 °C across different pyrolysis temperatures. The absorbed amounts of iodine in the aqueous solution ranged from 86 to 223 mg g-1 at a mass ratio of 1:1 between urban sludge and peach wood, which were comparably higher than those observed in other mass ratios. This study advances water treatment by offering a cost-effective method by using biochar derived from the processing of urban sludge and garden waste.

Experimental and Quantum Chemical Calculations on the High-Efficiency Transesterification of Dimethyl Carbonate with Alcohol Catalyzed by Calcium Oxide.

Typical catalysts used in dimethyl carbonate (DMC) transesterification encounter challenges in terms of environmental sustainability and economic viability. Calcium oxide (CaO), being an environmentally friendly and cost-effective catalyst, exhibits favorable compatibility with the criteria above. It has been conclusively demonstrated that CaO performs high efficiency as a catalyst for the transesterification between alcohols and DMC. The optimal conditions for the CaO-catalyzed transesterification of DMC and 1-octanol were determined (90 °C, 17 h, and CaO/1-octanol/DMC molar ratio = 0.3:1.0:40.0), under which the conversion of 1-octanol reaches 98.3%, while the yield and selectivity of methyl octyl carbonate are 98.1 and 99.9%, and CaO has been proven to have the efficient ability to be recycled three times. Meanwhile, the CaO-catalyzed reaction mechanism of the transesterification of DMC with alcohol is illustrated in the quantum chemical method based on the M06-2X functional, and the structures of the corresponding transition states are simultaneously derived. The activation energy barrier is proven to be effectively decreased by the catalytic effect of CaO. In addition, the electrostatic potential diagram verifies the proposed reaction sites. This research constructs the theoretical basis for CaO-based DMC chemistry and expands the green catalysts available for the synthesis of dialkyl carbonates.

Carbon leaching from peat soils of the north of Western Siberia under different hydrological conditions

Frozen peat soils in the north of Western Siberia are vulnerable to the on-going climate changes. The increase in temperature which affects the permafrost thaw returns the huge carbon stocks to the global element cycle. Its export in the form of dissolved organic matter from peatlands is determined by a number of factors, among which hydrological conditions are the least studied. The influence of hydrological regimes on carbon export from oligotrophic peat soils in discontinuous permafrost zone was investigated in laboratory conditions. The model column experiment allowed estimating the carbon yield from undisturbed (monolithic) peat samples of different degrees of decomposition. Three types of mesocosms were considered: undisturbed samples of the TO horizon, as well as the TO horizon with underlying material of different texture (sand and loam). The concentration of dissolved organic carbon in the lysimetric waters of a fibric peat does not differ for the “precipitation” and “snowmelt” simulating modes, and in the “stagnation” mode it is 1.4 times less. Sapric peat lysimetric waters show no differences under simulating hydrological regimes. The total export of organic carbon for three successive extractions for fibric peat is 32% higher than for sapric peat. An increase in carbon in the sandy material after three cycles of the experiment was revealed, the loamy material did not show significant differences. The carbon adsorption by mineral soil layers of the study area can be a protective mechanism that prevents increased runoff from the soils.

Biocarbon Production Using Three-Stage Pyrolysis and Its Preliminary Suitability to the Iron and Steel Industry

There has been a rising interest in the iron and steel industry in replacing fossil-based carbon carriers in their processes because they are the main origin of the anthropogenic carbon emissions within the industry. The use of bio-based carbon carriers could be one solution to partly tackle this challenge. Conventionally, biocarbon is produced by pyrolysis with fixed heating rate, pyrolysis temperature, and retention time. Although the mechanisms behind the formation of biocarbon and the decomposition temperatures of the main compounds of biomass-based materials are known, this knowledge is rarely being utilized in the design of commercial pyrolysis reactors, even though the pyrolysis mechanism-based approach increases the biocarbon yield. In this study, the mechanistic pathway of carbonization of lignocellulosic biomass is taken into account to produce biocarbon with higher yield and quality than conventional pyrolysis with the same process time. Results show that when the process time is the same in both methods, segmented pyrolysis increases biocarbon yield up to 5.4% within a pyrolysis temperature range from 300 °C to 900 °C. Also, fixed carbon yield increased 1.5% in this temperature area. When using segmented pyrolysis, the most suitable pyrolysis temperature is 700 °C based on the characteristics of the produced biocarbon.

Oxidative conversion of methane: maximizing the carbon yield in natural gas valorization via the C123 process

The Oxidative Conversion of Methane (OCoM) reactor, within the C123 process, is a novel concept for methane valorization into a product stream with a molar C2H4/CO/H2 composition of 1/1/1, i.e., suitable for further hydroformylation. This overcomes the limitations traditionally encountered during the Oxidative Coupling of Methane in the pursuit of a maximum ethylene yield. An experimental assessment was performed using a MnNaW/SiO2 catalyst under industrially relevant conditions (T=850°C, ptot=100 kPa, Wcat/FCH4,in = 2–2.5 kgcat s mol-1, CH4/O2 inlet molar ratio = 3 – 5 mol mol-1 and inlet CO2 molar fraction <20%) as a basis for kinetic model development. Simultaneously pursuing a C2H4/CO/H2 molar ratio of 1/1/1 and a maximum C2 yield, the impact of the operating conditions on the OCoM performance was simulated. Three different real feedstocks were assessed: natural gas, shale gas and biogas. Shale gas exhibited the highest OCoM potential, with as optimal operating conditions T=850°C, Wcat/FCH4,in = 6.5 kgcat s mol-1, CH4/O2 inlet molar ratio = 10 mol mol-1. The achieved C2H4/CO/H2 molar ratio amounted to 1/1.1/3.7 with a carbon yield (ethylene + CO) of 28% mol mol-1 and ethylene yield of 19% mol mol-1. Last, the considerations to validate the C123 process viability are given.