Preface

Today's chemical industry processes worldwide largely depend on catalytic reactions and the desirable future evolution of this industry toward more selective products, more envi‐ ronmentally friendly products, more energy-efficient processes, a smaller use of hazardous reagents, and a better use of raw materials also largely involves the development of better catalysts and specifically, purposely designed catalytic materials. For instance, the world's petroleum industry (oil refining and petrochemical industries) almost completely rely on catalytic processes. The catalyst market is considered to amount for more than 20 billion USD in 2015 and currently growing at a rate of approximately 4% per year.

Most people know that a catalyst is a facilitator of a chemical reaction, as stated in secon‐ dary/medium level education text books; however, the careful study and the development of the new generation catalysts involve considerable or relatively large groups of specialists in universities, research centers, and industries, joining forces from different scientific and technical disciplines. In 1835, Berzelius described a catalyst as a substance capable of acceler‐ ating a chemical reaction that can be recovered at the end of the reaction. Catalysts can be divided into two broad general groups: homogeneous catalysts (those in the same physical phase as the reactants, mostly liquids or gases) and heterogeneous catalysts (mostly solids, thereafter also known as catalyst materials). Some of the first solid catalysts were metals o metal compounds, still in use nowadays, whereas many other different types of catalysts have arisen along the years. Platinum, palladium, gold, cobalt, nickel, copper, and iron are some important metal catalysts, either in bulk or supported. Metal oxides, such as alumina, titania, zirconia, magnesia, ceria, or iron oxide, that constitute a principal group of catalytic materials is also the case of microporous and mesoporous molecular sieves: silica, alumina, zeolite, MCM-41, SBA-15, aluminophosphates (ALPOs), silicoaluminophosphates (SAPOs), metal organic frameworks (MOFs), and activated carbon or pillared clays. To complete the picture, we should include a wide range of proteins and enzymes, forming the biocatalysts group.

This book has put together recent state-of-the-art topics on current trends in catalytic materi‐ als and consists of 16 chapters. To divide the book's 16 chapters into the sections has not been easy because many of the individual chapters do not deal only with one type of cata‐ lyst or with one type of application. Contributions come from around the world: Australia, China, Japan, Korea, Turkey, Denmark, Poland, Switzerland, Sweden, Italy, Spain, Mexico, and the United States. Part 1 is dedicated to powerful characterization techniques based on X-ray spectroscopy: resonant X-ray emission spectroscopy (RXES) and high-energy resolu‐ tion off-resonant spectroscopy (HEROS). These characterization techniques provide new in‐ sights into the electronic structure of materials, molecular adsorption, and understanding catalytic reactions. Part 2 is dedicated to selected metal-based and structured porous cata‐

lysts (and their ample range of applications), such as nano-zero-valent-iron (nZVI), iron ox‐ ides, nanoferrites, zinc glutarate, metal-organic frameworks (MOFs), titanium-modified SBA-15, graphene oxide–hausmannite (Mn3O4) composites, and metal oxides, supported on silica. The largest section of the book is Part 3, comprising seven chapters on photocatalysis, from the reaction basics and a review of materials available to specific new materials and developments. Photocatalytic processes have received much attention because of the poten‐ tial of using sun light (possibly the more available renewable energy) and new environmen‐ tally friendly "green" technologies. Part 4 is focused on materials for electrocatalytic applications (such as sensors and energy conversion and storage): silver–copper nanoalloys and graphene–metal oxide nanohybrid materials, covering the synthesis, structure, and properties of the materials. Final section, Part 5, reviews the extensive field of biotechnology applications of synthetic DNA catalysts.

Finally, the editors, we like to acknowledge the motivation and expertise provided by all the authors, some of them starting a promising career with bright ideas and some of them con‐ solidated in the field with a remarkable background; constructing this book has been a sev‐ eral steps journey and they have maintained committed with the task. However, we also like to acknowledge InTech's editorial staff and their valuable support all along the way.

> **Dr. Luis Enrique Noreña** Department of Basic Sciences Universidad Autonoma Metropolitana, Azcapotzalco, Mexico

> > **Dr. Jin-An Wang** ESIQIE, Instituto Politecnico Nacional, Zacatenco, Mexico

**Specialized Characterization**

lysts (and their ample range of applications), such as nano-zero-valent-iron (nZVI), iron ox‐ ides, nanoferrites, zinc glutarate, metal-organic frameworks (MOFs), titanium-modified SBA-15, graphene oxide–hausmannite (Mn3O4) composites, and metal oxides, supported on silica. The largest section of the book is Part 3, comprising seven chapters on photocatalysis, from the reaction basics and a review of materials available to specific new materials and developments. Photocatalytic processes have received much attention because of the poten‐ tial of using sun light (possibly the more available renewable energy) and new environmen‐ tally friendly "green" technologies. Part 4 is focused on materials for electrocatalytic applications (such as sensors and energy conversion and storage): silver–copper nanoalloys and graphene–metal oxide nanohybrid materials, covering the synthesis, structure, and properties of the materials. Final section, Part 5, reviews the extensive field of biotechnology

Finally, the editors, we like to acknowledge the motivation and expertise provided by all the authors, some of them starting a promising career with bright ideas and some of them con‐ solidated in the field with a remarkable background; constructing this book has been a sev‐ eral steps journey and they have maintained committed with the task. However, we also like to acknowledge InTech's editorial staff and their valuable support all along the way.

> **Dr. Luis Enrique Noreña** Department of Basic Sciences

> > Mexico

Zacatenco, Mexico

**Dr. Jin-An Wang**

Universidad Autonoma Metropolitana, Azcapotzalco,

ESIQIE, Instituto Politecnico Nacional,

applications of synthetic DNA catalysts.

X Preface
