Synthesis of Electrocatalysts for Electrochemistry in Energy

The increasing population demands clean and green energy, encouraging scientists and technologists to make their best effort to develop renewable, available, and low-cost acquisition of non-conventional energy. Researchers in Catalysis and Electrochemistry, working together, have reached good achievements when focused in electrochemistry studies that are under development for alternative, renewable, capture, conversion, storage, supply, uses, and applications of energy. This is called Electrochemistry in energy. The symbiosis Electrochemistry-Catalysis is fundamental in this field for successful results. Important achievements are nowadays found in literature and some of them are reported here with emphasis in the use of electrochemistry for electrosynthesis of the named photoelectrocatalysts. Thus, photoelectrocatalysts, photocatalysts, and catalysts are of importance in many of the aspects involved in the term Electrochemistry in energy. This is such a wide field, with many aspects presented here, that the authors give an appropriate view and pedagogical standpoint for the readers.

Pretreatment of Lignocellulosic Biomass Feedstocks for Biofuel Production

The shifting of dependence from conventional fuels to renewable fuels and its increased production to combat the energy, environmental, and geopolitical crises is a global concern. One of the viable and promising alternatives is liquid biofuel production using lignocellulosic biomass. Lignocellulosic biomass being the most abundant encompass cellulose, hemicellulose, and lignin.The intricate complex of hemicellulose and lignin around cellulose is the bottleneck in commercializing the biofuel process. To make the cellulose and hemicellulose more accessible for hydrolysis and valorise the underutilized lignin for platform chemical production, pretreatment becomes imperative. Various pretreatment methods such as physical, mechanical, chemical, biological, and enzymatic and their combinations are employed for the production of bioethanol. It should be stressed that each pretreatment is unique in its condition and in most cases are biomass specific. With the above view, this chapter aims at bringing out the understanding of lignocellulosic pretreatment with updated information in the field.

Ultrasound-Assisted Synthesis of Nanostructured Oxide Materials

This chapter is focused on the use of high intensity ultrasound for the preparation of nanostructured materials with an emphasis on recent prominent examples of the production of dense or porous metal oxides through sonochemical and ultrasonic spray pyrolysis routes. Sonochemistry enables the synthesis of oxides that are often unachievable by traditional methods or affords known materials with shape, size, and nano/microstructure control under fast reaction conditions. The fundamental principles of acoustic cavitation, as well as the main ultrasonic parameters affecting the cavitation phenomenon, are first summarized. Next, the applications of ultrasound in the synthesis of nanostructured oxide materials following both preparation methods are reviewed. Particular focus is given to the ultrasound-assisted synthesis of metal oxide nanoparticles for energy applications.

Advances in Theoretical Studies on Solid Catalysts for Renewable Energy Production

This chapter presents a brief review of the recent applications of the quantum chemical calculations in the catalysis for renewable energy production. In this, an introductory vision about the use of ab initio calculations in the field of the renewable energies is presented. It is worth mentioning that the quantum chemistry field is an extensive area with many methodologies and theoretical approaches; therefore, to shed some light on the application of this area on the catalysis for renewable energy production, the chapter is divide into two sections according to the employed theoretical approximation, that is, the cluster model approach and the periodic approach. The first section describes the cluster model approximation, followed by a discussion of recent works in hydrogen storage, biodiesel and methanol conversion fields, and the second section describes the basic principles of the periodic approximation, basis set used in this approximation, and illustrative examples in the catalysts for biodiesel production; reforming of methane and hydrogen storage are presented at the end of this section.

Electrochemical Techniques as a Tool for Catalysts' Characterization

Two recently developed electrochemical techniques are presented as tools for the characterization of solid surfaces with possible catalytic or electrocatalytic capacities. The techniques are the voltammetry of immobilized micro particles (VIMP) and the electrochemical scanning microscopy (SECM). The VIMP is a simple and economical technique that only requires basic electrochemical instrumentation. Higher sophistication is possible with relatively low investments for non-specialized laboratories. The SECM requires more investment and technical advice because it requires a somewhat sophisticated instrumentation not usually found in an electrochemical laboratory. However, associated costs are relatively low compared to other solid surface exploration techniques. The historical development, improvements over time, and some applications for surface characterization are presented for each technique. Finally, some cases of coupling with other techniques allowing the expansion of the capacities for the topographical and reactivity characterization of solid surfaces are briefly presented.

CO2 Reduction by Photocatalysis on TiO2

This chapter focuses on the recent research progress on TiO2-based photocatalysts for CO2 reduction. The scope of this chapter for photoreduction of CO2 is set to focus on the most widely studied TiO2-based photocatalysts, composites, and systems since 1979. In addition, several important kinds of other related photocatalysts will be introduced briefly.

Mesoporous Silicas as Basic Heterogeneous Catalysts for the Formation of Biodiesel

The principal aspects of the production of biodiesel using heterogeneous catalysis are presented, comparing this alternative process to conventional (homogeneous) processes and evaluating the main operational parameters. The most important techniques for the preparation and characterization of silicas with basic properties are mentioned, dividing these materials into two groups with distinct properties: as-synthesized silicas, especially the M41S family, with their pores occluded with organic cations, and functionalized silicas, with accessible pores. The catalytic properties of these silicas were evaluated in transesterifications using a model reaction and vegetable oil. Finally, a brief presentation is made of other solid catalysts with basic properties that can be used in the biodiesel production reaction.

Non-Conventional Feedstock and Technologies for Biodiesel Production

Increased consumption and energy security issues have led many developed and developing countries to seek methods to produce alternative fuels. Biodiesel is one such high-density alternative fuel that can increase the longevity of transportation fuels. Biodiesel can be produced from a wide range of feedstock using simple process schemes. In the past, edible oils were used as feedstock for biodiesel fuel production; however, use of non-traditional feed stock like waste cooking oil, non-edible oils, animal fats, and algae can make biodiesel production a sustainable process. The high free fatty acids content in the feedstock, longer reaction rates, high energy consumption, and the catalysts used in the conversion process pose some limitations for current biodiesel production. These limitations can be addressed by developing novel process techniques such as microwaves and ultrasound and by developing non-catalytic transesterification methods. Enhancing byproduct recovery seems to be an important strategy to improve the energy footprint and economics of current biodiesel production.

Case Study

The effect of zirconium on the textural and catalytic properties of magnetite for the water gas shift reaction (WGSR) at high temperatures was studied in this chapter. The reaction is an important step in the industrial production of pure hydrogen. Samples with different amounts of zirconium (Zr/Fe (molar)= 0.1; 0.2;0.3; 0.4 and 0.5) were prepared from the decomposition of iron(III)hydroxoacetate doped with zirconium. It was found that zirconium increased the specific surface area of magnetite acting as spacer on the surface where it keeps the particles apart. Except for the zirconium-poorest solid, tetragonal zirconia was detected besides magnetite for all solids. Zirconium increased the intrinsic activity of the catalysts, stabilized the specific surface areas during reaction, and made the magnetite reduction to metallic iron more difficult. The zirconium-poorest is more active than magnetite and more resistant against deactivation by sintering and overreduction being attractive for WGSR.

Dry Reforming of Methane on LaSrNiAl Perovskite-Type Structures Synthesized by Solution Combustion

A comprehensive study of the effect of the combustion fuel (i.e., glycine and sucrose), ignition source (i.e., furnace and microwave radiation), and nickel content is carried out for the dry reforming of methane (DRM) using La0.6Sr0.4NiyAl1-yO3 (LaSrNiAl) (y = 0.1; 0.2 and 0.3) perovskite-type catalyst precursors synthesized by solution combustion synthesis (SCS). The composition of the catalyst precursor and the combustion fuel rather than the ignition source affected markedly the crystalline phase composition, crystallite size, morphology, specific surface, and reducibility. Those changes are also reflected in the catalytic performance of the SCS-prepared catalyst in the reaction of DRM. The results clearly show that the SCS approach can effectively tune the dry reforming of methane and the reverse water-gas shift reactions by varying the combustion fuels.