Biomass to Hydrogen via Fast Pyrolysis and Catalytic Steam Reforming of the Pyrolysis Oil or Its Fractions

Abstract

Pyrolysis of lignocellulosic biomass and reforming of the pyroligneous oils are being studied as a strategy for producing hydrogen. A process of this nature has the potential to be cost competitive with conventional means of producing hydrogen. We propose a regionalized system of hydrogen production, where small- and medium-sized pyrolysis units (<500 Mg/day) provide bio-oil to a central reforming unit to be catalytically converted to H2 and CO2. Thermodynamic modeling of the major constituents of the bio-oil has shown that reforming is possible within a wide range of temperatures and steam-to-carbon ratios. In addition, screening tests aimed at catalytic reforming of model compounds to hydrogen using Ni-based catalysts have achieved essentially complete conversion to H2. Existing data on the catalytic reforming of oxygenates have been studied to guide catalyst selection. A process diagram for the pyrolysis and reforming operations is discussed, as are initial production cost estimates. A window of opportunity clearly exists if the bio-oil is first refined to yield valuable oxygenates so that only a residual fraction is used for hydrogen production.

Steam Reforming of Bio-Compounds with Auto-Reduced Nickel Catalyst

“…At 650 • C, the bio-compound conversion decreased in this order: ethanol ≈ acetone > glucose > furfural > acetic acid. It was noticed that the conversion of ethanol was incomplete even at 750 • C, indicating that the catalyst used, a commercial catalyst for CH 4 conversions exhibited an increasing trend with temperature, similar to that observed for the light bio-compounds. Therefore, the bottleneck temperature for an effective conversion of glucose or furfural to gaseous products was 600 °C.…”

“…The main problem for SR of ethanol was a high CH 4 yield that was probably caused by ethanol decomposition. According to previous studies, this problem was common to neutral alcohols and could be solved by acidification of the reforming feedstock.…”

Oxidation of Fuels in the Cool Flame Regime for Combustion and Reforming for Fuel Cells.

“…Provided that the catalyst temperahire is above 923 K, acetic acid was almost completely converted to hydrogen and crubon oxides. Reforming the complex oxygenates seems chemically possible, using nickel based catalysts, but it may require high steam to carbon ratios because oxygenates rapidly dehydroxylate, which results in the formation of aromatics on the surface of the catalyst [127]. This work on the reforming of oxygenates concords with our hypothesis that the reaction products of cool flame treated fiiels, which are predominately formed by oxygenates, have potential for reforming.…”

Catalysis Research of Relevance to Carbon Management: Progress, Challenges, and Opportunities

“…Wet biomass and organic wastes could be efficiently gasified under hydrothermal conditions to produce a hydrogen-rich fuel gas. One approach is the hydrothermal conversion of organic material with the addition of alkali metals at high pressures in water, 70 such as the gasification of glucose in hot water at 600°C and 300 bar. This provides a much higher thermal efficiency, an H 2 -rich (60%) gas with low CO yield in one step, suppressed tar formation, without the need for extensive N or S removal.…”