Preparation of highly dispersed lignite-char-supported cobalt catalyst for stably steam reforming of biomass tar at low temperature

Oxygen-Vacancy-Rich Co–Ce/C for Highly Stable Catalytic Steam Reforming of Toluene at Low Temperature

“…It will increase the rate of side reactions such as the polycondensation reaction, causing a large amount of carbon to be formed on the catalyst surface. The active sites will be covered by the carbon layer, resulting in catalyst deactivation gradually. , However, the side reactions will be weakened by Co-5Ce/C with stronger basicity. Additionally, the effect of more dispersed active metal particles, higher reduction degree, and stronger MSI of Co-5Ce/C provided its better stability even under such extreme reaction conditions.…”

“…In addition to Ni-based catalysts, recently many researchers have found that Co can be an alternative to Ni due to its equally excellent cracking capacity as well as good oxophilicity, which can both improve the activity and stability for tar steam reforming, especially at low temperatures . Just as reported by our previous studies, − lignite char supported Co catalyst (Co/C) prepared via an ion exchanging method has highly dispersed small Co particle (3.77 nm), large specific surface area (SSA), stronger MSI and high metal reduction degree, achieving stable toluene conversion for 100 h at 400 °C and a steam to carbon ratio (S/C) of 0.68. Despite the fact that the growth of active Co size attributed to metal sintering was well restricted, a slight deactivation was also observed because of the fast carbon deposition, which would lead to micropore blockage and active site coverage.…”

Recent Progress of Catalysts for Reforming of Biomass Tar/Tar Models at Low Temperatures – A Short Review

“…Similarly, Wang et al [40] found the same type of carbon with TEM analysis. Additionally, Tang et al [29] reported that the amorphous carbon/encapsulating carbon may exist on the spent catalyst surface after being used for 100 h. Consequently, just as reported by these literatures, the encapsulating carbon can cover the active metal sites and block some pores on the support, thus causing the loss of active sites and hindering the mass transfer. However, the filamentous carbons may detach the active metal from the support and destruct the porous structure of catalysts, which can weaken the metal-support interaction.…”

“…Based on this, some studies have found that catalysts prepared from organic-derived Ni precursors (such as Ni(CH 3 COO) 2 ) have a moderate Ni reduction degree, a higher Ni dispersion and a smaller Ni particle size, which leads to a higher H 2 yield and a lower carbon deposition during the steam reforming reaction. Moreover, Tang et al [29] also reported that the catalyst Co 0.15 -C 2 H 3 O 2 À prepared with an ion-exchange method using the Co(CH 3 COO) 2 solution with lignite as the carbon precursor exhibits a better structure than using the Co(NO 3 ) 2 and the CoCl 2 solution. With a smaller Co particle size, a higher dispersion of Co, a stronger interaction between Co and support and less oxygen-containing impurities, Co 0.15 -C 2 H 3 O 2 À achieves a nearly 100 % conversion of toluene for the steam reforming reaction at 400 °C.…”

“…Finally, more H 2 is produced due to the rearrangement of aromatic rings in the polycyclic structure above 500 °C. Our group [28,29] also stated that tar is transformed into light tar, coke and gaseous products by cracking and homogeneous reforming reactions. After that, the light tar undergoes reforming reaction with steam and CO 2 followed with the break of CÀ C, CÀ H and CÀ O with the presence of active metals, resulting in the formation of small molecular gases, such as H 2 , CO and CO 2 .…”