Coprocessing Biomass Fast Pyrolysis and Catalytic Fast Pyrolysis Oils with Vacuum Gas Oil in Refinery Hydroprocessing

Fast pyrolysis and catalytic fast pyrolysis (CFP) have been considered to be promising approaches for converting lignocellulosic biomass into liquid bio-oils followed by upgrading to produce fuel-range hydrocarbon products. Coprocessing fast pyrolysis and CFP bio-oils with petroleum feedstocks leverages the existing petroleum refining infrastructure, which reduces capital expenditure for the overall conversion technologies for biomass to fuel and enables fast adoption of the technologies and biofuels. Here, we reported the coprocessing of different woody fast pyrolysis and CFP bio-oils with petroleum vacuum gas oil (VGO) at 5–25% bio-oil blending levels over a NiMo sulfide catalyst for hydrotreating/mild hydrocracking. The catalyst activities over ∼300 h time on stream, the product yield and properties, and the biogenic carbon content in products are provided. Coprocessing of the raw fast pyrolysis bio-oil in our configuration was not successful because the instability of the bio-oil resulted in reactor plugging, and bio-oil stabilization by hydrogenation enabled their stable coprocessing with VGO, whereas the CFP bio-oil can be coprocessed without pretreatment. Simultaneous hydrodesulfurization, hydrodeoxygenation, and hydrocracking reactions occurred during coprocessing, and no obvious decrease in hydrodesulfurization and hydrocracking conversion of VGO was observed, suggesting the minimal impact of coprocessed bio-oils on the reaction of VGO and also the simultaneous conversion of bio-oil and VGO to produce fuel products with much-reduced S and O content. Biogenic carbon content in coprocessed products calculated by yield mass balance, together with results from isotopic measurements, indicates biogenic carbon incorporation into liquid hydrocarbon products. Higher biogenic carbon incorporation into fuel products was observed when coprocessing CFP bio-oils as compared to the fast pyrolysis bio-oils, and over 90% of carbon in CFP bio-oil was incorporated into liquid hydrocarbon products

Steam Reforming of Acetic Acid over Co-Supported Catalysts: Coupling Ketonization for Greater Stability

We report on the markedly improved stability of a novel 2-bed catalytic system, as compared to that of a conventional 1-bed steam reforming catalyst, for the production of H₂ from acetic acid. The 2-bed catalytic system consists of (i) a basic oxide ketonization catalyst for the conversion of acetic acid to acetone, and (ii) a Co-based steam reforming catalyst, both catalytic beds placed in sequence within the same unit operation. Steam reforming catalysts are particularly prone to catalytic deactivation when steam reforming acetic acid, used here as a model compound for the aqueous fraction of bio-oil. Catalysts consisting of MgAl₂O₄, ZnO, CeO₂, and activated carbon (AC) both with and without Co-addition were evaluated for conversion of acetic acid, and its ketonization product, acetone, in the presence of steam. It was found that over the bare oxide support only ketonization activity was observed, and coke deposition was minimal. With addition of Co to the oxide support steam reforming activity was facilitated, and coke deposition was significantly increased. Acetone steam reforming over the same Co-supported catalysts demonstrated more stable performance and with less coke deposition than with acetic acid feedstock. DFT analysis suggests that, over Co, surface CH_<i>x</i>COO species are more favorably formed from acetic acid versus acetone. These CH_<i>x</i>COO species are strongly bound to the Co catalyst surface and could explain the higher propensity for coke formation from acetic acid. On the basis of these findings, in order to enhance stability of the steam reforming catalyst, a dual-bed (2-bed) catalyst system was implemented. Upon comparison of the 2-bed and 1-bed (Co-supported catalyst only) systems under otherwise identical reaction conditions, the 2-bed demonstrated significantly improved stability, and coke deposition was decreased by a factor of 4