Research

Jump to: Review

19 pages, 2413 KiB

Open AccessArticle

Coupled Biohydrogen Production and Bio-Nanocatalysis for Dual Energy from Cellulose: Towards Cellulosic Waste Up-Conversion into Biofuels

by Jaime Gomez-Bolivar, Rafael L. Orozco, Alan J. Stephen, Iryna P. Mikheenko, Gary A. Leeke, Mohamed L. Merroun and Lynne E. Macaskie

Catalysts 2022, 12(6), 577; https://doi.org/10.3390/catal12060577 - 24 May 2022

Cited by 1 | Viewed by 1532

Abstract

Hydrogen, an emergent alternative energy vector to fossil fuels, can be produced sustainably by fermentation of cellulose following hydrolysis. Fermentation feedstock was produced hydrolytically using hot compressed water. The addition of CO₂ enhanced hydrolysis by ~26% between 240 and 260 °C with [...] Read more.

Hydrogen, an emergent alternative energy vector to fossil fuels, can be produced sustainably by fermentation of cellulose following hydrolysis. Fermentation feedstock was produced hydrolytically using hot compressed water. The addition of CO₂ enhanced hydrolysis by ~26% between 240 and 260 °C with comparable hydrolysis products as obtained under N₂ but at a 10 °C lower temperature. Co-production of inhibitory 5-hydromethyl furfural was mitigated via activated carbon sorption, facilitating fermentative biohydrogen production from the hydrolysate by Escherichia coli. Post-fermentation E. coli cells were recycled to biomanufacture supported Pd/Ru nanocatalyst to up-convert liquid-extracted 5-HMF to 2,5-dimethyl furan, a precursor of ‘drop in’ liquid fuel, in a one-pot reaction. This side stream up-valorisation mitigates against the high ‘parasitic’ energy demand of cellulose bioenergy, potentially increasing process viability via the coupled generation of two biofuels. This is discussed with respect to example data obtained via a hydrogen biotechnology with catalytic side stream up-conversion from cellulose feedstock. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Figure 1

24 pages, 1911 KiB

Open AccessArticle

Trends in Widely Used Catalysts for Fatty Acid Methyl Esters (FAME) Production: A Review

by Shafaq Nisar, Muhammad Asif Hanif, Umer Rashid, Asma Hanif, Muhammad Nadeem Akhtar and Chawalit Ngamcharussrivichai

Catalysts 2021, 11(9), 1085; https://doi.org/10.3390/catal11091085 - 09 Sep 2021

Cited by 26 | Viewed by 4937

Abstract

The effective transesterification process to produce fatty acid methyl esters (FAME) requires the use of low-cost, less corrosive, environmentally friendly and effective catalysts. Currently, worldwide biodiesel production revolves around the use of alkaline and acidic catalysts employed in heterogeneous and homogeneous phases. Homogeneous [...] Read more.

The effective transesterification process to produce fatty acid methyl esters (FAME) requires the use of low-cost, less corrosive, environmentally friendly and effective catalysts. Currently, worldwide biodiesel production revolves around the use of alkaline and acidic catalysts employed in heterogeneous and homogeneous phases. Homogeneous catalysts (soluble catalysts) for FAME production have been widespread for a while, but solid catalysts (heterogeneous catalysts) are a newer development for FAME production. The rate of reaction is much increased when homogeneous basic catalysts are used, but the main drawback is the cost of the process which arises due to the separation of catalysts from the reaction media after product formation. A promising field for catalytic biodiesel production is the use of heteropoly acids (HPAs) and polyoxometalate compounds. The flexibility of their structures and super acidic properties can be enhanced by incorporation of polyoxometalate anions into the complex proton acids. This pseudo liquid phase makes it possible for nearly all mobile protons to take part in the catalysis process. Carbonaceous materials which are obtained after sulfonation show promising catalytic activity towards the transesterification process. Another promising heterogeneous acid catalyst used for FAME production is vanadium phosphate. Furthermore, biocatalysts are receiving attention for large-scale FAME production in which lipase is the most common one used successfully This review critically describes the most important homogeneous and heterogeneous catalysts used in the current FAME production, with future directions for their use. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Figure 1

15 pages, 4036 KiB

Open AccessFeature PaperArticle

Thermogravimetry of the Steam Gasification of Calluna vulgaris: Kinetic Study

by José María Encinar, Juan Félix González and Sergio Nogales-Delgado

Catalysts 2021, 11(6), 657; https://doi.org/10.3390/catal11060657 - 22 May 2021

Cited by 3 | Viewed by 1509

Abstract

On account of the continuous decrease in oil reserves, as well as the promotion of sustainable policies, there is an increasing interest in biomass conversion processes, which imply the search for new raw materials as energy sources, like forestry and agricultural wastes. On [...] Read more.

On account of the continuous decrease in oil reserves, as well as the promotion of sustainable policies, there is an increasing interest in biomass conversion processes, which imply the search for new raw materials as energy sources, like forestry and agricultural wastes. On the other hand, gasification seems to be a suitable thermal conversion process for this purpose. This work studied the thermogravimetry of the steam gasification of charcoal from heather (Calluna vulgaris) in order to determine the kinetics of the process under controlled reaction conditions. The variables studied were temperature (from 750 to 900 °C), steam partial pressure (from 0.26 to 0.82 atm), initial charcoal mass (from 50 to 106 mg), particle size (from 0.4 to 2.0 mm), N₂ and steam volumetric flows (from 142 to 446 mL·min⁻¹) and catalyst (K₂CO₃) concentration (from 0 to 10% w/w). The use of the shrinking core model and uniform conversion model allowed us to determine the kinetic parameters of the process. As a result, a positive influence of catalyst concentration was found up to 7.5% w/w. The kinetic study of the catalytic steam gasification showed activation energies of 99.5 and 114.8 kJ·mol⁻¹ and order of reactions (for steam) of 1/2 and 2/3. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Graphical abstract

14 pages, 6526 KiB

Open AccessArticle

Laboratory-Scale Research of Non-Catalyzed Supercritical Alcohol Process for Continuous Biodiesel Production

by Aso A. Hassan and Joseph D. Smith

Catalysts 2021, 11(4), 435; https://doi.org/10.3390/catal11040435 - 29 Mar 2021

Cited by 8 | Viewed by 2313

Abstract

This work investigates the non-catalyzed supercritical methanol (SCM) process for continuous biodiesel production. The lab-scale setup was designed and used for biodiesel production in the temperature range of 520–650 K and 83–380 bar with an oil-to-methanol molar ratio ranging from 1:5 to 1:45. [...] Read more.

This work investigates the non-catalyzed supercritical methanol (SCM) process for continuous biodiesel production. The lab-scale setup was designed and used for biodiesel production in the temperature range of 520–650 K and 83–380 bar with an oil-to-methanol molar ratio ranging from 1:5 to 1:45. The experiments were performed in the coiled plug flow tubular reactor. The volumetric flow rate of the methanol/oil ranged from 0.1–10 mL/min. This work examines a new reactor technology involving preheating and pre-mixing of the methanol/oil mixture to reduce setup cost and increase biodiesel yield under the same reaction conditions. Work performed showed that FAME’s yield increased rapidly with temperature and pressure above the methanol critical points (i.e., 513 K and 79.5 bar). The best methyl-ester yield using this reaction technology was 91% at 590 K temperature and 351 bars with an oil-to-methanol ratio of 39 and a 15-min residence time. Furthermore, the kinetics of the free catalyst transesterification process was studied in supercritical methanol under different reaction conditions. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Figure 1

17 pages, 2865 KiB

Open AccessFeature PaperArticle

Catalyzed Steam Gasification of Cistus Ladanifer Biochar

by José María Encinar, Juan Félix González and Sergio Nogales-Delgado

Catalysts 2020, 10(12), 1430; https://doi.org/10.3390/catal10121430 - 07 Dec 2020

Cited by 4 | Viewed by 1521

Abstract

Gasification processes require the use of cheap and sustainable raw materials, as well as the optimization of the process, for a suitable commercial use. Cistus Ladanifer (rockrose) could be a suitable raw material for this purpose, as it grows spontaneously in Mediterranean regions, [...] Read more.

Gasification processes require the use of cheap and sustainable raw materials, as well as the optimization of the process, for a suitable commercial use. Cistus Ladanifer (rockrose) could be a suitable raw material for this purpose, as it grows spontaneously in Mediterranean regions, and might contribute to the economic development of these areas. In this research, a study about catalyzed gasification of Cistus Ladanifer biochar was carried out. The aim was to characterize the gaseous phase and to carry out a kinetic study. The experiments were carried out in a thermobalance connected to a gas chromatograph to quantify the exhaust gas. The operating variables studied were the initial carbon mass, temperature, steam partial pressure, the kind of catalyst (ionic or cationic), catalyst concentration and the method to incorporate the catalyst (impregnation or mixture). As a result, impregnation was the most effective way to mix the raw material and the catalyst, with K⁺ and CO₃²⁻ as the most active cations and anions used in this experience, respectively. Temperature and steam partial vapor showed a positive effect on conversion and gas yield. The use of ideal models for gas-solid reactions showed acceptable results for the kinetic study. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Graphical abstract

14 pages, 2800 KiB

Open AccessArticle

Production of Biodiesel from Brown Grease

by Mirit Kolet, Daniel Zerbib, Faina Nakonechny and Marina Nisnevitch

Catalysts 2020, 10(10), 1189; https://doi.org/10.3390/catal10101189 - 15 Oct 2020

Cited by 19 | Viewed by 5895

Abstract

Among the renewable energy sources is biodiesel. This fuel is usually produced by catalytic transesterification of vegetable oils and animal fats under heating and pressure. Brown grease is a mixture of oils, fats, solids and detergents from food industry wastes that is captured [...] Read more.

Among the renewable energy sources is biodiesel. This fuel is usually produced by catalytic transesterification of vegetable oils and animal fats under heating and pressure. Brown grease is a mixture of oils, fats, solids and detergents from food industry wastes that is captured in grease traps. Brown grease is classified as waste and must be treated and disposed of appropriately. It contains oils and fats that can be converted into biodiesel. However, the high concentration of free fatty acids in brown grease does not enable the use of conventional biodiesel production schemes. This study proposes a new scheme for biodiesel production from brown grease. In addition, conditions for the effective separation of a fat phase from brown grease were tested, and the composition of a fatty phase was determined for several grease traps. Esterification and transesterification of brown grease lipids were carried out with methanol, where the Lewis acids BF₃ and AlCl₃ were used as catalysts and the reaction was activated by ultrasound. The results show that biodiesel can be obtained from brown grease by esterification and transesterification within several minutes under ultrasonic activation at room temperature. These results open prospects for the development of efficient, low-cost and environmentally friendly biodiesel production. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Figure 1

Review

Jump to: Research

30 pages, 4387 KiB

Open AccessReview

Single-Atom Catalysts: A Review of Synthesis Strategies and Their Potential for Biofuel Production

by Nurul Asikin-Mijan, Haslinda Mohd Sidek, Abdulkareem G. AlSultan, Nurul Ahtirah Azman, Nur Athirah Adzahar and Hwai Chyuan Ong

Catalysts 2021, 11(12), 1470; https://doi.org/10.3390/catal11121470 - 30 Nov 2021

Cited by 8 | Viewed by 3337

Abstract

Biofuels have been derived from various feedstocks by using thermochemical or biochemical procedures. In order to synthesise liquid and gas biofuel efficiently, single-atom catalysts (SACs) and single-atom alloys (SAAs) have been used in the reaction to promote it. SACs are made up of [...] Read more.

Biofuels have been derived from various feedstocks by using thermochemical or biochemical procedures. In order to synthesise liquid and gas biofuel efficiently, single-atom catalysts (SACs) and single-atom alloys (SAAs) have been used in the reaction to promote it. SACs are made up of single metal atoms that are anchored or confined to a suitable support to keep them stable, while SAAs are materials generated by bi- and multi-metallic complexes, where one of these metals is atomically distributed in such a material. The structure of SACs and SAAs influences their catalytic performance. The challenge to practically using SACs in biofuel production is to design SACs and SAAs that are stable and able to operate efficiently during reaction. Hence, the present study reviews the system and configuration of SACs and SAAs, stabilisation strategies such as mutual metal support interaction and geometric coordination, and the synthesis strategies. This paper aims to provide useful and informative knowledge about the current synthesis strategies of SACs and SAAs for future development in the field of biofuel production. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures

Figure 1

26 pages, 1829 KiB

Open AccessEditor’s ChoiceReview

Advances in Valorization of Lignocellulosic Biomass towards Energy Generation

by Ikram ul Haq, Kinza Qaisar, Ali Nawaz, Fatima Akram, Hamid Mukhtar, Xin Zohu, Yong Xu, Muhammad Waseem Mumtaz, Umer Rashid, Wan Azlina Wan Ab Karim Ghani and Thomas Shean Yaw Choong

Catalysts 2021, 11(3), 309; https://doi.org/10.3390/catal11030309 - 26 Feb 2021

Cited by 67 | Viewed by 7533

Abstract

The booming demand for energy across the world, especially for petroleum-based fuels, has led to the search for a long-term solution as a perfect source of sustainable energy. Lignocellulosic biomass resolves this obstacle as it is a readily available, inexpensive, and renewable fuel [...] Read more.

The booming demand for energy across the world, especially for petroleum-based fuels, has led to the search for a long-term solution as a perfect source of sustainable energy. Lignocellulosic biomass resolves this obstacle as it is a readily available, inexpensive, and renewable fuel source that fulfills the criteria of sustainability. Valorization of lignocellulosic biomass and its components into value-added products maximizes the energy output and promotes the approach of lignocellulosic biorefinery. However, disruption of the recalcitrant structure of lignocellulosic biomass (LCB) via pretreatment technologies is costly and power-/heat-consuming. Therefore, devising an effective pretreatment method is a challenge. Likewise, the thermochemical and biological lignocellulosic conversion poses problems of efficiency, operational costs, and energy consumption. The advent of integrated technologies would probably resolve this problem. However, it is yet to be explored how to make it applicable at a commercial scale. This article will concisely review basic concepts of lignocellulosic composition and the routes opted by them to produce bioenergy. Moreover, it will also discuss the pros and cons of the pretreatment and conversion methods of lignocellulosic biomass. This critical analysis will bring to light the solutions for efficient and cost-effective conversion of lignocellulosic biomass that would pave the way for the development of sustainable energy systems. Full article

(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)

► Show Figures