Heterogeneous Catalytic Conversion of Carbon Dioxide into 1,2-Butylene Carbonate and Styrene Carbonate

The significant increase of carbon dioxide (CO2) into the atmosphere is alarming since the industrial revolution and this has resulted to prevailing environmental challenges such as global warming experienced in recent times. There is an urgency to reduce CO2 emissions to a sustainable level in order to prevent global warming and climate change. Several methods of reducing CO2 emissions have been identified. However, greener synthesis of organic carbonates such as 1,2-butylene carbonate (BC) and styrene carbonate (SC) through the utilisation of CO2 have been identified to be valuable chemicals in chemical industry. The utilisation of CO2 to produce value-added chemicals is considered as one of the promising technological advancements targeted at reducing CO2 emissions to a sustainable level. 1,2-Butylene carbonate and styrene carbonate are promising green chemicals, which find their applications in chemical and pharmaceutical industries. These organic carbonates exhibit excellent chemical properties and can be used widely as intermediates to synthesise other chemicals, electrolyte to power lithium batteries and fuel additives. The syntheses of 1,2-butylene carbonate and styrene carbonate using conventional approaches involve the use of phosgene, a toxic feedstock and produce acid waste, which is highly toxic and environmentally unfriendly. The application of solvent-free heterogeneous catalytic processes promote green processes and offer more sustainable process for the syntheses of organic carbonates. In this work, batch experimental studies have been conducted using several commercially available heterogeneous catalysts such as ceria and lanthana doped zirconia (Ce–La–Zr–O), ceria doped zirconia (Ce–Zr–O), lanthana doped zirconia (La–Zr–O), lanthanum oxide (La–O), zirconium oxide (Zr–O) and graphene oxide supported inorganic nanocomposites where graphene oxide (GO) has been used as a suitable support and metal oxide catalyst (Ce-La-Zr/GO) has been extensively assessed for the synthesis of 1,2-butylene carbonate and styrene carbonate. Ceria, lanthana, zirconia doped graphene nanocomposites (Ce-La–Zr/GO) have been synthesised using a new innovative approach known as a continuous hydrothermal flow synthesis (CHFS) reactor. Copper, zirconia doped graphene oxide (Cu-Zr/GO) and copper, zirconia oxide/graphene composite (HTR450) have been synthesised using conventional wet impregnation methods and assessed as suitable heterogeneous catalysts for the synthesis of 1,2-butylene carbonate via a facile direct route. These catalysts have been characterised using various analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurement. The use of a solvent-free heterogeneous catalytic process for the direct syntheses of BC and SC have been conducted in a high-pressure reactor. Various reaction parameters such as the effect of reaction temperature, CO2 pressure, reaction time, catalyst loading, and stirring speed have been investigated to achieve the optimum reaction conditions on the conversion of epoxides and yield of cyclic carbonates. The long-term stability of the heterogeneous catalysts has been evaluated by conducting reusability studies. Copper, zirconia doped graphene nanaocomposite catalyst (HTR450) and ceria, lanthana, zirconia doped graphene oxide catalyst (Ce-La-Zr/GO) have been found to be the most active and selective for the synthesis of BC as compared to other commercial catalysts evaluated in this research work. For the direct synthesis SC, ceria, lanthana doped zirconia (Ce-La-Zr-O) has been found to be the best-performed catalyst as compared to other used catalysts. The reusability studies of these HTR450, Ce-La-Zr/GO and Ce-La-Zr-O catalysts have evidently shown the long-term stability without any significant reduction in their performances. Response Surface Methodology (RSM) in the design of experiment is used for modelling and optimisation of experiments in the process industry, catalysis and chemical reaction engineering. The application of RSM minimise the number of experiments thereby saving time and materials. Hence, RSM using box-Behnken design (BBD) has been explored to evaluate and optimise multiple responses (output variables), which are influenced by several independent variables such as catalyst loading, temperature, CO2 pressure, and reaction time. BBD model has been developed for the direct synthesis of SC via cycloaddition reaction of CO2 to styrene oxide (SO) and direct synthesis of BC through reaction of butylene oxide (BO) and CO2. The developed models have been used to compare the experimental results and the predicted results. Regression analyses have been carried out to establish the optimum reaction parameters for a maximum yield of SC and BC. The predicted values of BBD model are in good agreement with the experimental results with <1.5% error

A facile and greener synthesis of butylene carbonate via CO2 utilisation using a novel copper–zirconia oxide/graphene catalyst

The cumulative CO2 emissions in the atmosphere are causing serious changes in climate via global warming because of continuous burning of fossil fuel. However, the scientific community has identified the means to alleviate the environmental burden through carbon capture and storage, and utilisation of CO2 for synthesis of value added chemicals. The latter greener approach for utilising CO2 as a C1 feedstock for organic chemical synthesis is extremely beneficial not only for the chemical industry but also for contributing to limit its emissions. The direct synthesis of butylene carbonate (BC) through cycloaddition reaction of CO2 to butylene oxide (BO) is of a great commercial interest. BC is an excellent reactive intermediate material used in industry for the production of surfactant, plasticisers, polymers and can also be used as a solvent for wood binder resins, degreasing, paint remover, lubricants and the foundry, sand binders as well as lithium battery because of its high polarity property. Several reaction routes have been attempted for BC production, e.g. phosgene, oxidative carboxylation, direct synthesis using homogeneous catalyst and direct synthesis using a heterogeneous catalyst. The latter being the most attractive route due to the inexpensive raw material, ease of catalyst recovery and avoidance of corrosive reagents, such as phosgene. In the present work, a facile and environmentally benign method has been developed for the synthesis of highly efficient graphene-inorganic heterogeneous catalyst, represented as Cu–Zr/GO inorganic composite. The graphene-inorganic heterogeneous catalyst has been characterised using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and nitrogen adsorption/desorption method (for measuring BET surface area and pore size distribution). Copper-zirconia/graphene inorganic composite catalyst (Cu–Zr–GO) as heat treated at 723 K exhibited high catalytic activity as compared to other reported heterogeneous catalysts in the absence of any organic solvent with 71% yield of BC, and 87% selectivity towards BO at the reaction conditions of 423 K, 80 bar in 12 h. The use of Box-Behnken Design (BBD) from Response Surface Methodology (RSM) has been employed to investigate the single and interactive effect of several independent reaction variables that include temperature, pressure, catalyst loading, heat treatment and time, on the conversion of BO and yield of BC. Two quadratic regression models have been developed representing an empirical relationship between each reaction response and all the independent variables. The predicted models have been validated statistically and experimentally, where very high agreement has been observed between predicted and experimental results with approximate relative errors of ±1.25% for BO conversion and ± 0.75% for BC yield. Acknowledgments We acknowledge the financial support from London South Bank University and The British University in Egypt

Greener synthesis of 1,2-butylene carbonate from CO2 using graphene-inorganic nanocomposite catalyst

The synthesis of 1,2-butylene carbonate (BC) from cycloaddition reaction of 1,2-butylene oxide (BO) and carbon dioxide (CO2) was investigated using several heterogeneous catalysts in the absence of organic solvent. Continuous hydrothermal flow synthesis (CHFS) has been employed as a rapid and cleaner route for the synthesis of a highly efficient graphene-inorganic heterogeneous catalyst, ceria-lanthana-zirconia/graphene nanocomposite, represented as Ce–La–Zr/GO. The heterogeneous catalysts have been characterised using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and nitrogen adsorption/desorption (BET for measuring the surface area/pore size distribution),. Ceria- lanthana-zirconia/graphene nanocomposite catalyst (Ce–La–Zr/GO) exhibited high catalytic activity as compared to other reported heterogeneous catalysts in the absence of any organic solvent with a selectivity of 76% and 64% yield of 1,2-butylene carbonate at the reaction conditions of 408 K, 75 bar in 20 h

Greener synthesis of 1, 2 butylene carbonate from CO2 using graphene-inorganic nanocomposite catalysis

The global emission of carbon dioxide (CO2) into the atmosphere has reached an unsustainable level that has resulted in climate change and therefore there is the need to reduce the emission of CO2. However, the reduction of CO2 emission has become a global environmental challenge and the use of CO2 to produce value added chemicals could be one of the few ways of reducing CO2 emission. CO2 is recognised as an abundant, cheap, recyclable and non-toxic carbon source and thus its utilisation for the production of value-added chemicals is extremely beneficial for the chemical industry. 1,2-butylene carbonate is a valuable chemical of great commercial interest. It is an excellent reactive intermediate material used in industry for the production of plasticisers, surfactant, and polymers and can also be used as a solvent for degreasing, paint remover, wood binder resins, foundry sand binders, lubricants as well as lithium battery because of its high polarity property. Several reaction routes have been attempted for 1,2-butylene carbonate production, which was phosgene, oxidative carboxylation, direct synthesis using homogeneous catalyst and direct synthesis using a heterogeneous catalyst. The latter being the most attractive route due to the inexpensive raw material, ease of catalyst recovery and the avoidance of corrosive reagents, such as phosgene. Continuous hydrothermal flow synthesis (CHFS) has been employed as a rapid and cleaner route for the synthesis of highly efficient graphene-inorganic heterogeneous catalyst, represented as Ce–La–Zr–GO nanocomposite. The graphene-inorganic heterogeneous catalyst has been characterised using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), while X-ray powder diffraction (XRD) and Brunauer–Emmett–Teller (BET) methods have been used for the surface area measurements. Ceria, lanthana, zirconia doped graphene nanocomposite catalyst studies have shown high catalytic activity as compared to other reported heterogeneous catalysts in the absence of any organic solvent with a higher selectivity of 76% and 64% yield of 1,2-butylene carbonate at the reaction conditions of 408 K, 75 bar in 20 h

Greener synthesis of styrene carbonate from CO2 using graphene-inorganic nanocomposite catalysts

The global emission of carbon dioxide (CO2) into the atmosphere has reached an unsustainable level that has resulted in climate change and therefore there is the need to reduce the emission of carbon dioxide. However, the reduction of CO2 emission has become a global environmental challenge and the use of CO2 to produce value added chemicals could be one of the few ways of reducing CO2 emission. CO2 is recognised as an abundant, cheap, recyclable and non-toxic carbon source and thus its utilisation for the production of value-added chemicals is extremely beneficial for the chemical industry. Styrene carbonate is a valuable chemical of great commercial interest. It is an excellent precursor material for the production of polycarbonates and can be used as a solvent for lithium battery because of its high polarity property. Several reaction routes have been attempted for styrene carbonate production, which was phosgene, oxidative carboxylation, direct synthesis using homogeneous catalyst and direct synthesis using a heterogeneous catalyst. The latter being the most attractive route due to the inexpensive raw material, ease of catalyst recovery and the avoidance of corrosive reagents, such as phosgene and dimethyl formamide. Continuous hydrothermal flow synthesis (CHFS) has been employed as a rapid and cleaner route for the synthesis of highly efficient graphene-inorganic heterogeneous catalyst, represented as Ce–La–Zr–GO nanocomposite. The graphene-inorganic heterogeneous catalyst has been characterised using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), while X-ray powder diffraction (XRD) and Brunauer–Emmett–Teller (BET) methods have been used for the surface area measurements. Ceria, lanthana, zirconia doped graphene nanocomposite catalyst studies have shown high catalytic activity as compared to other reported heterogeneous catalysts in the absence of organic solvent with a higher selectivity of 68% and 60% yield of styrene carbonate at the reaction conditions of 408 K, 75 bar in 20 h

Greener synthesis of butylene carbonate via CO2 utilisation using graphene-inorganic nanocomposite catalysts

The synthesis of butylene carbonate (BC) through the reaction of butylene oxide (BO) and carbon dioxide has been investigated using highly efficient graphene-inorganic heterogeneous catalyst, lathana-cerium-zirconia and graphene oxide represented as La– Ce–Zr–GO nanocomposite. The catalysts have been extensively characterised using transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area measurement powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. Response Surface Methodology (RSM) using Box-Behnken Design (BBD) has been applied to optimise the single and interactive effect of four independent reaction variables, i.e. temperature, pressure, catalyst loading and time, on the conversion of BO and BC yield. Two quadratic regression models have been developed representing an empirical relationship between each reaction response and all the independent variables. The predicted models have been validated statistically and experimentally, where the high agreement was observed between predicted and experimental results with approximate relative errors of ±1.5% for both the conversion BO and the yield of BC

Next frontiers in cleaner synthesis: 3D printed graphene-supported CeZrLa mixed-oxide nanocatalyst for CO2 utilisation and direct propylene carbonate production

A rapidly-growing 3D printing technology is innovatively employed for the manufacture of a new class of heterogenous catalysts for the conversion of CO2 into industrially relevant chemicals such as cyclic carbonates. For the first time, directly printed graphene-based 3D structured nanocatalysts have been developed combining the exceptional properties of graphene and active CeZrLa mixed-oxide nanoparticles. It constitutes a significant advance on previous attempts at 3D printing graphene inks in that it does not merely explore the printability itself, but enhances the efficiency of industrially relevant reactions, such as CO2 utilisation for direct propylene carbonate (PC) production in the absence of organic solvents. In comparison to the starting powder, 3D printed GO-supported CeZeLa catalysts showed improved activity with higher conversion and no noticeable change in selectivity. This can be attributed to the spatially uniform distribution of nanoparticles over the 2D and 3D surfaces, and the larger surface area and pore volume of the printed structures. 3D printed GO-supported CeZeLa catalysts compared to unsupported 3D printed samples exhibited higher selectivity and yield owing to the great number of new weak acid sites appearing in the supported sample, as observed by NH3-TPD analysis. In addition, the catalyst's facile separation from the product has the capacity to massively reduce materials and operating costs resulting in increased sustainability. It convincingly shows the potential of these printing technologies in revolutionising the way catalysts and catalytic reactors are designed in the general quest for clean technologies and greener chemistry

Greener synthesis of styrene carbonate from CO2 using heterogeneous catalyst

Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas and therefore it is considered as the main contributor to global warming. However, CO2 is recognised as an abundant, cheap, recyclable and non-toxic carbon source and thus its utilisation for the production of value-added chemicals is extremely beneficial for the chemical industry. Styrene carbonate is a non-toxic, biodegradable and a valuable chemical of great commercial interest. Styrene carbonate is an excellent precursor material for the production of polycarbonates. Styrene carbonate can be used as a solvent for lithium battery because of its high polarity property. Several reaction routes have been attempted for styrene carbonate production, which was phosgene, oxidative carboxylation, direct synthesis using homogeneous catalyst and direct synthesis using a heterogeneous catalyst. The latter being the most attractive route due to the inexpensive raw material, ease of catalyst recovery and the avoidance of corrosive reagents, such as phosgene and dimethyl formamide. The research study is aimed at catalytic conversion of carbon dioxide (CO2) to value added chemicals as to reduce the emission of greenhouse gases in order to prevent global warming. The utilisation of carbon dioxide will not only offer one of the means to prevent global warming but also offer a mean of value-added chemicals such as fuel additives, substitute for various chemical reagents, organic solvent and green reagents. The synthesis of organic carbonate through cycloaddition of carbon dioxide to epoxide in the present of the heterogeneous catalyst using high-pressure reactor is known to be a ‘Green Processes’. Heterogeneous catalyst of metal oxides such as magnesium oxide, cerium oxide, zirconium oxide, lanthanum oxide, lanthana doped zirconia, magnesium oxide and cerium doped zirconium oxide ceria lanthana doped zirconia was used to synthesised styrene carbonate through cycloaddition of carbon dioxide to styrene oxide in a batch high-pressure reactor under different reaction conditions. Among other catalysts ceria lanthana doped zirconia catalyst showed good activity and selectivity for styrene carbonate without additional organic solvents. The optimum reaction conditions for the synthesis of styrene carbonate in the presence of ceria lanthana doped zirconia catalyst system was at 408 K, 75 bar, 20 h and 300 rpm with the corresponding yield of 52% and conversion of 84%

Systematic multivariate optimisation of butylene carbonate synthesis via CO <inf>2</inf> utilisation using graphene-inorganic nanocomposite catalysts

© 2019 The synthesis of butylene carbonate (BC) through the reaction of butylene oxide (BO) and carbon dioxide (CO 2 ) has been investigated using highly efficient graphene-inorganic heterogeneous catalyst, cerium-lanthana-zirconia and graphene oxide represented as Ce–La–Zr–GO nanocomposite. The systematic multivariate optimisation of BC synthesis via CO 2 utilisation using graphene-inorganic nanocomposite has been developed using Box-Behnken Design (BBD) of Response Surface Methodology (RSM). The BBD has been applied to optimise the single and interactive effect of four independent reaction variables, i.e. reaction temperature, pressure, catalyst loading and reaction time on the conversion of BO and BC yield. Two quadratic regression models have been developed representing an empirical relationship between each reaction response and all the independent variables. The predicted models have been validated statistically and experimentally, where a high agreement has been observed between predicted and experimental results with approximate relative errors of ±1.45% and ±1.52% for both the BO conversion and BC yield, respectively. The implementation of RSM optimisation process for the conversion of BC through the reaction between BO and CO 2 , has offered a new direction in green chemical process in terms of waste reduction, maximising production of value-added chemicals and effectively utilise CO 2 gas emissions