LAUSR

The present Special Issue concerns the papers which have been presented at the fifth edition of the Global Conference on Catalysis, Chemical Engineering & Technology (CAT 2019) that promote linkage of the catalytic science, engineering and technology. The topics of the conference have covered various aspects of catalysis in all of its diversity, as well as the areas of the chemical engineering and technology. Meloni et al. [1] have presented a short review on Ni based catalysts and related engineering issues for methane steam reforming. The steam reforming of methane is the most used process for production of hydrogen, an important raw material in chemical industries. In methane steam reforming process, the use of a catalyst is mandatory. Nibased catalysts give an acceptable high activity when compared to precious metal-based catalysts appeared much more expensive. The high activity and the low cost made Ni catalysts have been widely studied by the scientific community in methane steam reforming. Advancements in catalysis technologies and methods have improved the state of methane steam reforming, in particular the synthesis methods of nano-sized particles, including impregnation, co-sputtering, and chemical vapor deposition, allow for highly dispersed dopants and high activity. The researchers showed that the addition of metallic or bimetallic species to a Ni based catalyst can improve selectivity, durability, and activity, thus limiting the typical problems of the methane steam reforming, including coke formation, active oxidation, sintering, and segregation. This review evidenced that most common materials used as supports or support dopants are CeO2, ZrO2, and their mixed oxides, since their high oxygen storage capacity and redox properties lead to efficient coke resistance, which makes these materials advantageous over conventionally used Al2O3 or MgAl2O4. The complexity of the traditional steam reforming process involving many very different operation units is optimized for the industrial scale, limiting the possibility to realize process intensification. In the last years, the scientific research focused on the development of innovative hydrogen production systems as well as on the optimization of the conventional processes and, in this sense, the catalyst has a fundamental role. The steam reforming catalysts must meet stringent requirements, such as high activity, reasonable life, good heat transfer, low pressure drop, high thermal stability, and excellent mechanical strength. In addition, the necessity of reducing the costs made the development of methane steam reforming processes operating at low temperature mandatory, so avoiding, for example, the use of special steel alloy. The development of new catalysts with well-defined properties is fundamental in order to reach this objective: in fact, the catalyst must activate methane at low temperature, it must drive its conversion up to equilibrium values at short contact times and, in addition, it must be resistant to deactivation factors including carbon formation, which is favored at low temperature, and preferential oxidation, which occurs at low temperature mainly for Ni catalysts. The objective of a low temperature methane