Sibunit-Supported Mono- and Bimetallic Catalysts Used in Aqueous-Phase Reforming of Xylitol

Abstract

Carbon-supported mono- and bimetallic catalysts prepared via incipient wetness impregnation were systematically studied in aqueous-phase reforming (APR) of xylitol aiming at hydrogen production from biomass. The catalytic performance of several VIII group metals and their combinations, such as Pt, Ni, Pt–Ni, Re, Pt–Re, Ru, Pt–Ru, and Pt–Co, was compared for xylitol APR in a fixed-bed reactor at 225 °C and 29.7 bar (N2). Ni/C, Ru/C, and Re/C catalysts displayed significantly lower activity compared to others. Activity and selectivity to H2 of bimetallic Pt–Ni/C, Pt–Co/C, and Pt–Ru/C catalysts were close to that of Pt/C. Pt–Re/C catalyst showed an outstanding performance which was accompanied by a shift of the reaction pathways to the alkane formation and thereby lower hydrogen selectivity. Addition of the second metal to Pt was not found to be beneficial for hydrogen production, thus leaving Pt/C as the optimum carbon-supported catalyst.

Bimetallic Nanostructured Catalysts Prepared by Laser Electrodispersion: Structure and Activity in Redox Reactions

“…The contribution from MeC X species to the Pd3d, Ni2p and C1s spectra is lower for Sibunit-supported samples than for HOPGsupported ones due to the higher fraction of surface functional groups on the Sibunit. [27] Summarizing, we can conclude, that independently on the type of a support Ni and Pd in LED bimetallic systems are situated in close vicinity, may be in the composition of the same particles, as it is evident from EDS data. According to EDS and XPS studies (Table 2), the Ni/Pd atomic ratio in the samples produced by LED of NiPd alloy target on the surface of alumina or carbon supports (3-3.5) is close to this value in the initial alloy (about 3.35, or 77 : 23).…”

“…The former is flat and conducting, and therefore more suitable for model experiments, while the granulated Sibunit is commonly used as industrial adsorbent and catalyst carrier. [27] Typical XPS spectra of mono-and bimetallic Ni,Pd systems supported by LED on HOPG and Sibunit are presented in Figure 2. Ni2p 3/2 spectra were fitted with three components ( Table 1).…”

A Short Overview on the Hydrogen Production Via Aqueous Phase Reforming (APR) of Cellulose, C6-C5 Sugars and Polyols

“…The reactions are generally carried out under continuous flow conditions with hydrogen being produced in relatively good yields (20-40%) while using mono metallic (mainly Pt) based catalysts, in which the most investigated supports are well designed mesoporous carbon materials (e.g., Sibunit type, three dimensional bimodal carbons, activated carbons etc.) [28,30,31]. Alumina represents definitely the other most investigated support for both monometallic [29,32,33] and bimetallic or other way modified Pt-based catalyst [34][35][36].…”

“…It is noteworthy that production of alkanes can be boosted by the addition of Re. Indeed, bimetallic Pt-Re catalysts, supported over alumina or titania, have been proved to promote the formation of light alkanes (mainly propane, ethane, and methane), starting from xylitol or sorbitol [30,35]. This is probably due to the ReOx particles, dispersed over Pt, which favour the adsorption of the polyols and the selective hydrogenolysis of C-O bonds.…”

A two-step approach to hydrothermal gasification

“…Additionally, the high reactivity of the Ru catalyst is reflected in the increased carbon gasification. Considering The utilisation of bimetallic catalysts containing Pt and Ru has been studied in the field of APR [138][139][140]. Although such catalysts have been found to improve reactivity and reaction rates, this comes at the cost of reduced H 2 production due to its consumption in the formation of methane [140].…”