Niobium: The Focus on Catalytic Application in the Conversion of Biomass and Biomass Derivatives

Abstract

The world scenario regarding consumption and demand for products based on fossil fuels has demonstrated the imperative need to develop new technologies capable of using renewable resources. In this context, the use of biomass to obtain chemical intermediates and fuels has emerged as an important area of research in recent years, since it is a renewable source of carbon in great abundance. It has the benefit of not contributing to the additional emission of greenhouse gases since the CO2 released during the energy conversion process is consumed by it through photosynthesis. In the presented review, the authors provide an update of the literature in the field of biomass transformation with the use of niobium-containing catalysts, emphasizing the versatility of niobium compounds for the conversion of different types of biomass.

Efficient Conversion of Lignin to Aromatics via Catalytic Fast Pyrolysis over Niobium-Doped HZSM-5

“…Second, the introduction of Nb (V), which has a unique electronic and energy band structure, provided H[Nb]ZSM-5 with the abilities to generate aromatics via direct phenol deoxygenation, similar to the formation of aromatics observed over CoO/MoO 3 [ 17 ]. This also agrees with literature that reports niobium oxide-based catalysts are effective in catalytic cleavage of C–O bonds [ 31 , 32 ]. In conclusion, the synergistic catalytic effect of Nb (V) and HZSM-5 could cleave both sp 2 and sp 3 C–O–C linkages of lignin vapors and further transform the resultant oxygenates into aromatics via deoxygenation, thus improving the selectivity of monocyclic aromatic products.…”

“…Furthermore, the aromatic product contents obtained in our work were compared with those elsewhere in the literature where lignin was pyrolyzed through a similar or identical experimental device under similar conditions [ 31 , 32 ] ( Table 6 ). The total aromatic hydrocarbon yield obtained from H-ZSM-5 in this study was approximately 35.5%, which is consistent with values reported in the literature (32% in ref.…”

“…In recent years, owing to the special electronic structure Nb 5c , metal Nb-modified molecular sieves have attracted great attention for the effective catalytic cracking of C-O bonds [ 31 , 32 ]. Yang [ 31 ] et al synthesized NbAlS-1 by integrating Nb (V) and Al (III) active sites into an MFI-type zeolite framework.…”

“…In addition, a synergistic catalytic effect of Nb (v) sites and Brønsted acid sites in promoting C-O bond breaking was found. Wang [ 32 ] et al prepared a Nb-doped SBA-15 molecular sieve by hydrothermal synthesis and applied it in 2, 5-dimethyltetrahydrofuran hydrodeoxygenation to prepare hexane. This proved that the Nb active sites with a low coordination number could effectively activate a C-O bond in the hydrodeoxidation reaction.…”

Chemical valorisation of biomass derived furanics and carboxylic acids over niobium-based catalysts

“…In this sense, niobium based oxides may be promising acid catalysts since they may be relatively water-tolerant 48,49 for various biomass conversion routes 50 involving reactions such as dehydration, 49,[51][52][53] etherification, alcoholysis, 54 acetalization, 55 hydrolysis and esterification. 56,57 According to the literature, niobium oxides may possess Brønsted and Lewis acidity capable of activating carbon-oxygen bonds and oxygencontaining functional groups, 58 accounting for superior performances compared to those of other metal oxides such as MgO, CaO, MgAl hydrotalcites, Al 2 O 3 , and ZrO 2 in Fur/4-heptanone condensation. 59 Zeolites were modified with niobium in order to trigger Fur condensation, 60 and a preliminary study showed good catalytic potential of niobium oxide nanoparticles wrapped within a mesoporous silica component.…”