Reactive catalytic fast pyrolysis (RCFP) of biomass with atmospheric pressure hydrogen is a promising route for the deoxygenation of biomass pyrolysis vapors while retaining high carbon yields in the bio-crude. RCFP process development was accomplished in a bench-scale bubbling fluidized-bed reactor with in situ catalyst configuration. Results are presented that highlight the impact of temperature, biomass weight hourly space velocity (WHSV), reaction pressure, and time on stream on the hydrodeoxygenation of different oxygen-containing species produced during biomass reactive catalytic fast pyrolysis to improve the bio-crude product yield and quality. The highest bio-crude and C 4+ hydrocarbons yield was 46.5 wt % on a carbon basis. The optimal temperature range for RCFP is 450−475 °C; the biomass WHSV should be kept low, around 0.6 h −1 in this reactor system, to produce a low oxygen content bio-crude (7.2 wt %), and improvements in the bio-crude yield and quality based on increased pressure are less significant beyond 2.7 bar. The product composition varies by at most 10% for up to 3.5 h' time on stream (biomass-to-catalyst ratio of 2.6 g g −1 ), indicating a stable catalyst activity for hydrodeoxygenation.

This study investigates hydrotreating biocrude produced by reactive catalytic fast pyrolysis (RCFP), a direct biomass liquefaction process that combines a robust hydrodeoxygenation catalyst for in situ pyrolysis with excess hydrogen at ambient (low) pressure. The RCFP process leverages advantages from catalytic fast pyrolysis (process simplicity and improved biocrude quality) and biomass hydropyrolysis (enhanced hydrodeoxygenation) to produce a thermally stable biocrude that can be upgraded in a single hydroprocessing step or coprocessed with petroleum refining intermediates to produce gasoline- and diesel-range hydrocarbons. RCFP biocrude (9.4 kg, 19.3 wt % oxygen, dry basis) was hydrotreated continuously for 144 h, in a pilot-scale hydroprocessing unit, at 138 barg (2000 psig) hydrogen pressure, 0.31 h–1 space velocity, and an average temperature of 300 °C. Blends of 10%, 15%, and 20% RCFP biocrude in light gas oil were also upgraded over a NiMo hydrotreating catalyst at 350 °C in hydrogen at 50–70 barg (725–1015 psig). The stand-alone hydrotreating results indicate that, even though there was no pressure drop increase indicative of reactor fouling, hydrotreating catalyst deactivation was evident as the product density increased from 0.852 to 0.955 kg/L after 144 h time-on-stream. Additionally, the oxygen content of the upgraded liquid product increased from 1.4 wt % to 5.5 wt % over the course of the experiment. In the coprocessing test, little or no catalyst deactivation was observed with the 10% RCFP blend on the basis of the density of the hydrotreated products. However, the hydrotreating catalyst activity was lower during upgrading of the 20% and 15% blends. On the basis of hydrodesulfurization of light gas oil, the relative activity of the hydrotreating catalyst decreased by 40% during the 1000 h coprocessing test. Fortunately, this level of deactivation measured at this small scale does not correlate to a prohibitively large deactivation rate at the industrial scale.

A pilot-scale biomass catalytic pyrolysis unit with a nominal throughput of one tonne of biomass per day (1TPD) has been in operation since 2013 to investigate the process parameters that have the largest influence on biocrude yield, oxygen content, and chemical composition. A parametric study was conducted to investigate the effect of pyrolysis temperature, ranging from 433 to 581 °C, on biocrude yield and quality. A locally sourced loblolly pine feedstock and a commercially available, spray dried, nonzeolitic γ-Al2O3 catalyst were used in individual experiments conducted at each pyrolysis temperature to achieve a minimum of 4 h of steady-state continuous operation. Typically, 600–800 kg of biomass was fed over a 12-h period, with one experiment extended to almost 29 h (1144-kg biomass fed) and one experiment interrupted by a process upset after just 7 h (411-kg biomass fed). Comprehensive analysis of collected gas, liquid, and solid products were used to calculate carbon balances (77% to 107%) for each experiment. The biocrude yield ranged from 12 to 18 wt % C and, in general, decreased with increasing pyrolysis temperature. The average steady-state biocrude yield as a function of temperature translated to a biocrude production rate between 40 and 50 gallons per dry ton. The biocrude oxygen content varied between 21 and 31 wt %, on a dry basis, and as expected, decreased with increasing pyrolysis temperature. The identified components in the semivolatile biocrude products are mostly methoxyphenols and other multiphenolic compounds. The multiphenolic compounds are demethoxylated at pyrolysis temperatures above 500 °C, producing biocrudes with higher concentrations of monophenols and polycyclic aromatic hydrocarbons. The concentration of anhydrosugars, like levoglucosan in the biocrudes, decreased with increasing pyrolysis temperature from ∼15 to ∼1 vol %.