Reactive catalytic fast pyrolysis (RCFP) of biomass with atmospheric pressure hydrogen was investigated in a lab-scale fluidized bed reactor with varying reaction conditions (temperature and hydrogen concentration) and catalysts. Presence of atmospheric hydrogen with candidate RCFP catalysts was found to improve the yield and quality of bio-crude and minimize the char and coke formation. A molybdenum-based catalyst was the most effective at hydrodeoxygenating biomass pyrolysis vapors to produce a hydrocarbon-rich bio-crude intermediate with low oxygen content (<10 wt%). Higher hydrogen concentration and moderate reaction temperature (450 °C) favored higher bio-crude yields and quality. A yield of 43.2 C% in the C₄₊ organic fraction with as low as 6.2 wt% oxygen in the liquid was obtained under optimized reaction conditions. The resulting bio-crude contained primarily aliphatic and aromatic hydrocarbons, with small amounts of simple ketones, furans, and phenols. Up to 41.5% carbon in the biomass feed was converted into gas and condensable hydrocarbons with 29.7% in the condensable C₄₊ fraction. The improved bio-crude quality is expected to be more compatible with existing petroleum refining infrastructure.

We report on a new pyrolytic pathway for biomass conversion to hydrocarbon fuel precursors. The process entails the conversion of multifunctional oxygenates generated from biomass pyrolysis over a metal oxide catalyst into ketonic-rich monofunctional molecules suitable for making hydrocarbon fuel components for gasoline, diesel, and jet fuel. A number of catalysts were explored, for example, anatase TiO₂ nanorods, CeO_x–TiO₂ mixed oxides, pure CeO₂, ZrO₂, and MgO. Under pyrolysis conditions, ceria-based catalysts were effective in the conversion of hydroxy-carbonyls, anhydrosugars, and carboxylic acids into acetone, 2-butanone, pentanones, C6/C7 ketones, cyclopentanone, and 2-cyclopentenones. The highest carbon yield (23.5%) of ketonic precursors was achieved on the pure CeO₂.

Amino alkylation of technical lignins via the Mannich reaction can be used as an analytical derivatization technique, but it is also used to improve kraft lignin hydrophilicity or metal ion adsorptive capacity. Recent studies have indicated the potential for increased amination under acidic conditions; however, the effects of pH on the amination of kraft lignins remain poorly understood because indirect quantification methods are often used. A quantitative technique combining 2D HSQC NMR and ¹³C NMR spectroscopy was used in this study to directly probe the structure of high and low molecular weight fractions of an industrial pine kraft lignin aminated in acidic or basic media with dimethylamine or diethylamine. The degree of amine substitution was two times higher for low molecular weight lignin compared to the high molecular weight fraction. Neither pH nor amine species had any significant effect. New evidence confirms that amine substitution of pine kraft lignin takes place selectively ortho to non-etherified phenolic hydroxyl groups and displaces carboxylic acid groups of benzoic- and cinnamic-type subunits. Other pathways were proposed and tested, but substitution did not occur at sterically hindered sites. Elemental analysis has been the most widely used indicator of Mannich condensation, but unfortunately overestimates amine substitution because nitrogen-containing side products and impurities can be included in the total nitrogen content. Multiple methods should always be employed when characterizing complex, heterogeneous biopolymers like lignins to avoid misinterpretation of results.

Single-stage hydrotreating (HDT) of loblolly pine biocrude produced from catalytic pyrolysis was conducted to gain insight to HDT performance in terms of product yields, liquid product quality, and hydrogen consumption. Tests were performed with a sulfided HDT catalyst at three different conditions. The longest continuous time onstream operation (365 h) was achieved at an average bed temperature of 290 °C, 138 bar pressure, H₂/oil ratio of 3300 Nl l⁻¹, and a liquid hourly space velocity (LHSV) of 0.25 h⁻¹. The average carbon yield of the HDT liquids were 77%, 83%, and 89% for experiments 1, 2, and 3, respectively. Also, the biocrude carbon that ended up in the gas phase varied between 4.3% and 8.9%. The carbon in the aqueous phase fraction was negligible—less than 0.5% of the biocrude carbon. The average hydrogen consumed ranged from 0.04 g to 0.07 g per 1 g of dry biocrude. The highest carbon content measured for the HDT liquid products from all three experiments was 87.13 wt% and the lowest was 79.03 wt%. GC-MS analysis suggests that the HDT product with oxygen content less than 5 wt% contained mainly naphthenic hydrocarbons. On the other hand, HDT products with oxygen content greater than 5 wt% contained a higher concentration of simple phenols and aromatic hydrocarbons (mono- and poly-). Catalyst deactivation was evident in the quality of the HDT liquid collected over time; the density and viscosity increased, the H/C ratio and carbon contents decreased; also, the gasoline fraction decreased while the gas oil fraction increased. The results from this work suggest that HDT of biocrude produced by catalytic biomass pyrolysis can be successfully upgraded into hydrocarbon liquid fuels without a stabilization step.

Selective method for separation of phenolic compounds from biomass pyrolysis liquids.