Demand For Renewable Fuels Research Articles

Advances in Metal Oxide‐based Nanocatalysts for Biodiesel Production: A Review

AbstractThe demand for renewable fuels has risen as a result of increasing human population, urbanization, industrialization, and transport systems. Biodiesel production using metal oxide‐based heterogeneous catalysts is an efficient, sustainable, and environmentally friendly approach. Because of their recovery, reusability, and consistency, heterogeneous catalysts may be preferable to homogeneous catalysts. Since the last few decades, the metal oxides of alkali earth and transition metals and their composite materials have been used as nanocatalysts in the production of biodiesel fuel. Utilization of inorganic metal oxide nanoparticles (MONPs) and their composite materials in producing biodiesel has gained increased attention because of their advanced physical and chemical characteristics. In this review, the applicability of metal oxides and their nanocomposite‐based catalysts in biodiesel production, transesterification reactions with nanocatalytic systems, and the important parameters that affect these reactions are discussed.

Bioreactor and process design for 2G ethanol production from xylose using industrial S. cerevisiae and commercial xylose isomerase

Second-generation ethanol has gained attention since the increase in demand for renewable fuels, but some issues still impair its feasibility, such as the conversion of xylose from biomass. Many routes can be explored for this purpose, but Simultaneous Isomerization and Fermentation (SIF) stand out due to the possibility of working with robust, non-genetically modified Saccharomyces cerevisiae strains. This work addresses bioreactor and process designs for SIF, using high enzyme and yeast load in their commercial forms, that can be introduced in the current ethanol-sugar industry. Characterization of two xylose isomerases (IGI-HF and Sweetzyme) in SIF conditions showed that both are suitable for the process. Between two industrial yeast strains evaluated, S. cerevisiae “Itaiquara” (baker’s yeast) was selected due to its superior xylulose assimilation. Problems with mass transfer and cell damage due to the presence of enzyme particles at high loads were faced, and different strategies were evaluated. Promising ethanol productivity (0.87 gEtOH/L/h, for 50 gDCW/L and 53,000 IU/L) was achieved using an enzyme-multiple-packed bed reactor. In addition, it allowed easy enzyme recovery and reuse, enabling its application in repeated batch operations integrated into the 1G ethanol process.

Metal–Organic Frameworks for CO2 Separation from Flue and Biogas Mixtures

AbstractGreat efforts have been made toward the separation of CO2 from flue gas and biogas to mitigate environmental pollution and the demand for renewable fuels, respectively. Nonthermal‐based separations, such as adsorption‐based or membrane‐separation technology employing porous materials, are considered to be more promising than traditional cryogenic and absorption‐based systems. Due to several advantages of metal–organic frameworks (MOFs) over other conventional porous materials, reports on flue and biogas separation by MOFs are burgeoning (423 for adsorption and 56 for membrane‐based separations until June 2021) and demand urgent summarization. This review presents a bird's eye view on such separations while organizing the developed strategies and considering several performance parameters, such as trade‐off between sorption capacity and separation selectivity in adsorption‐based systems and permeability versus separation selectivity in membrane‐based systems. In addition, the mechanisms involving such separations at the molecular level are presented. A critical discussion section offers more crucial insights into these materials from industrial deployment viewpoints. Finally, future recommendations are made for further developments of MOF materials as flue and biogas separators and thus toward solving both the challenging universal problems of global warming and energy scarcity simultaneously.

Study of the Integrated Product Recovery by Gas Stripping for the Abe Fermentation with a Fed-batch Fermenter

Because of the growing demand for renewable fuels, the production of butanol through acetone-butanol-ethanol (ABE) fermentation of lignocellulosic biomasses has been recently attracting an increasing research interest.The major limit for an industrial-scale production of bio-butanol is the high separation cost, due to the presence of other fermentation products and to its low final concentration in the broth. In fact, the microorganism used in the ABE fermentation suffers from product inhibition leading to a low ABE final concentration in a batch process. The application of an integrated product recovery technique able to remove butanol during fermentation is a viable solution to solve the problem and to improve the economics of the ABE fermentation.In this context, gas stripping has been proven to be an effective separation technique, able to reduce the inhibition of the microorganism and, therefore, to increase the process productivity.However, gas stripping usually removes a large amount of water together with butanol and requires a higher energy input, because of its lower butanol selectivity, in comparison with other separation techniques. To improve the performances of the integrated fermentation-gas stripping process for butanol production, optimization of gas stripping and fermenter conditions, and a better understanding of its effects on the ABE fermentation is needed.This study deals with the synthesis of a process configuration for the integrated recovery of butanol from a fermentation unit operated in a fed-batch mode, in which the product is recovered from the fermentation broth by means of nitrogen gas stripping and is, subsequently, fractionated in a distillation train. For the studied configuration, a detailed simulation of the integrated recovery process including the fed-batch fermenter and the downstream separation train has been performed. The simulation results have been used to evaluate the effect of the integrated product recovery on the process productivity and on the total energy consumption, which has been quantified through the net equivalent fuel approach. Finally, the performances of the integrated process have been compared with the ones obtained with a traditional batch fermentation, in order to assess the potential of the proposed process solution.

Morpho-anatomical aspects and technological quality of saccharine sorghum submitted to plant regulators

Com o aumento na demanda de combustíveis renováveis, a indústria sucroenergética tem tido como desafio o aumento da produtividade agroindustrial, além da redução dos custos de produção. Atualmente, são escassos os relatos da utilização de reguladores vegetais na cultura do sorgo sacarino. O objetivo deste trabalho foi avaliar aplicação dos reguladores vegetais na qualidade tecnológica e aspectos morfoanatômicos do sorgo sacarino. O ensaio foi realizado na usina Cerradinho em Catanduva SP. As aplicações dos reguladores vegetais foram: etephon nas dosagens de 1,32, 0,66, 0,33 L ha-1, sulfometuron-methyl nas dosagens de 20, 10, 5 g ha-1, thiadizuron nas dosagens de 0,150, 0,100, 0,50 L ha-1, ethyl-trinexapac nas dosagens de 0,80, 0,40, 0,20 L ha-1 e controle. O experimento foi conduzido em Blocos Casualizados, no esquema de parcelas subdivididas com quatro repetições. Foram avaliadas as variáveis tecnológicas: pureza do caldo, açúcares redutores, açúcares totais recuperáveis, brix do caldo, pol do caldo, açúcares teóricos recuperáveis, fibra (%) e mensurados: espessura da epiderme da face adaxial (EAD); espessura da epiderme da face abaxial (EAB); diâmetro do esclerênquima (DE); espessura do mesofilo (MF); diâmetro dos vasos xilemáticos (DX) e diâmetro dos vasos floemáticos (DF). Para as características tecnológicas, os maturadores químicos sulfometuron-methyl e etephon nas doses 5 g ha-1 e 0,33 L ha-1, respectivamente, promoveram os melhores resultados a partir dos 37 dias após a aplicação. Para as características morfonatômicas, o maturador químico thiadizuron na dose 0,100 L ha-1 apresentou os melhores resultados aos 44 dias após a aplicação.

Using modern tools to probe the structure-function relationship of fatty acid synthases.

Fatty acid biosynthesis is essential to life and represents one of the most conserved pathways in nature, preserving the same handful of chemical reactions across all species. Recent interest in the molecular details of the de novo fatty acid synthase (FAS) has been heightened by demand for renewable fuels and the emergence of multidrug-resistant bacterial strains. Central to FAS is the acyl carrier protein (ACP), a protein chaperone that shuttles the growing acyl chain between catalytic enzymes within the FAS. Human efforts to alter fatty acid biosynthesis for oil production, chemical feedstock, or antimicrobial purposes has been met with limited success, due in part to a lack of detailed molecular information behind the ACP-partner protein interactions inherent to the pathway. This review will focus on recently developed tools for the modification of ACP and analysis of protein-protein interactions, such as mechanism-based crosslinking, and the studies exploiting them. Discussion specific to each enzymatic domain will focus first on mechanism and known inhibitors, followed by available structures and known interactions with ACP. Although significant unknowns remain, new understandings of the intricacies of FAS point to future advances in manipulating this complex molecular factory.

Genetic divergence and phosphorus use efficiency in the soybean with a view to biodiesel production

The soybean has an important role in the area of biodiesel, due to having a productive potential and technical feasibility able to meet the growing demand for renewable fuels. In the agricultural year of 2009/10, four competitive trials of soybean cultivars were carried out, two on the Campus of Palmas University and the other two on the University Campus at Gurupi, with a study of genetic divergence being undertaken. At each location, the cultivars were trained under conditions of both high and low phosphorus (150 kg ha -1 P 2 O 5 and 30 kg ha -1 P 2 O 5 respectively). The experimental design employed for each trial was of randomised blocks with three replications and 11 treatments. The percentage of oil as a characteristic was studied, and the efficiency of phosphorus usage by the cultivars determined employing the methodology adapted from Fischer (1983). Genetic divergence was evaluated using multivariate procedures: the generalised Mahalanobis distance and Tocher's optimisation method for clustering. In the study of genetic divergence, each test represented a distinct variable in the multivariate model. The cultivars M-SOY 9350, M 8766RR and BR/EMGOPA 314 are the most suitable for the production of biodiesel. The hybrids M 8766RR x M 9056RR, BR/EMGOPA 314 x M 9056RR, P98R91 x M 9056RR are promising for obtaining segregating populations to be used for their oil content.