Graphitized nanocarbon materials can be an ideal catalyst support for heterogeneous catalytic systems. Their unique physical and chemical properties, such as large surface area, high adsorption capacity, excellent thermal and mechanical stability, outstanding electronic properties, and tunable porosity, allow the anchoring and dispersion of the active metals. Therefore, currently they are used as the key support material in many catalytic processes. This review summarizes recent relevant applications in supported catalysts that use graphitized nanocarbon as supports for catalytic oxidation, hydrogenation, dehydrogenation, and C-C coupling reactions in liquid-phase and gas-solid phase-reaction systems. The latest developments in specific features derived from the morphology and characteristics of graphitized nanocarbon-supported metal catalysts are highlighted, as well as the differences in the catalytic behavior of graphitized nanocarbon-supported metal catalysts versus other related catalysts. The scientific challenges and opportunities in this field are also discussed. Keywords: nanocarbon materials; graphitized carbon supports; metal catalysts; hetergeneous catalysis
INTRODUCTIONCarbon combines its atoms in diverse hybridization states (sp, sp 2 , sp 3 ) to form a variety of polymorphs. These are composed entirely of carbon but have different physical structures and different names, including diamond, graphite, fullerenes, and carbines, among others [1][2][3][4][5]. Because these various and versatile allotropes produce materials with a large range of properties, carbon materials can be used in a number of technological processes, including high-tech catalytic ones [6][7][8][9][10].In heterogeneous catalysis, carbon material plays wellestablished and important roles in a wide range of applications, both as catalyst in its own right and as a unique support material [11][12][13][14][15]. The chemical stability of carbon supports in some specifically aqueous phase biomass conversion surpasses that of metal oxide materials; in addition, carbon materials present other common and key advantages as support materials for catalysis [1,5]. From the point of physical structure, porous carbon can be prepared in different forms (granules, cloth, fibers, pallets, etc.). Due to its chemical properties, carbon structure is resistant to both acidic and basic media. The structure of carbon is stable at high temperature (even above 1023 K under inert atmosphere). The hydrophilic/ hydrophobic nature of carbon can be easily modified. Active metals on the support can be easily reduced. For the purposes of industrial economy and environment, the active phase can be easily recovered. Conventional carbon supports are lower-cost and more easily available than other conventional supports. Although several kinds of carbon materials have been studied, active carbon (AC) [12,[16][17][18][19] and, to a lesser extend, carbon black [20][21][22][23] have long been the most commonly used carbon supports. AC is an amorphous solid prepa...