Reactive catalytic fast pyrolysis with atmospheric pressure hydrogen improved yield and quality of the resulting bio-crude.

Introduction. Carbon nanotubes have extremely high thermal conductivities; single-walled carbon nanotubes (SWCNTs) have been predicted through molecular dynamics modeling to have a thermal conductivity up to 6600 W/(m K). 1 This value is more than 10 times the value for copper and 2 times more than the highest thermally conductive diamond. An obvious SWCNT application would therefore be a high thermally conductive dispersion for applications such as heat conducting composites 1 or heat transfer fluid suspensions. 2 Using Maxwell's mixing theory, SWCNTs should increase a polymer's thermal conductivity by 50-fold at a volume fraction of ∼1 vol %. Experiments have shown that such improvements do not happen in practice, and improvements, if any, are at least an order of magnitude less than expected. [3][4][5] This lack of improvement is due to the presence of an interfacial resistance to heat transfer between the solid nanotubes and the surrounding matrix termed the Kapitza resistance. This name has been given because Kapitza first measured such interfacial resistances in 1941 with experiments on metal-liquid helium interfaces. 6 A complete description of the cause of this resistance is beyond the scope of this paper, but in short, the Kapitza resistance occurs because of modulus mismatch between the matrix and the inclusion; the greater the mismatch, the greater the resistance. 7,8 The Kapitza resistance becomes more significant with increasing filler surface area and is extremely high in composites with carbon nanotubes because of their high stiffness as well as their high surface area. 9,10 Because of its importance, this type of resistance is still being studied today through experiments and computational models. 11 Duong et al. 3,12 reported Monte Carlo simulation results for heat transfer through carbon nanotube composites that produced conductivity improvements similar to experimental results. Work by Gonnet et al. 1 showed that magnetically aligned carbon nanotube mats (bucky paper) have a relatively high thermal conductivity (42 W/(m K) at ambient temperature). However, after incorporating them in epoxy, the thermal conductivity drops to that of random composites. 1 Although we do not doubt the correctness of the theory, experimentalverificationoftheKapitzaresistanceinpolymer-matrix nanocomposites is not a trivial task. Work by Yodh et al. 5 found a difference in thermal conductivity for composites processed with and without surfactant and attributed the larger increase in thermal conductivity for the surfactant-processed samples to the surfactant layer modifying this interfacial resistance; however, there was no way to know that the dispersion quality was the same. The work by Gonnet et al. 1 described briefly above is certainly persuasive; however, the bucky paper network might have been affected by infusion and curing of the epoxy. One obvious direct comparison would be to measure the thermal conductivity of two polymers with differing moduli filled to identical levels with nanotubes or some other high c...

Catalytic hydropyrolysis of loblolly pine was studied in a high-pressure fluidized bed reactor using a NiMo hydrotreating catalyst. Hydropyrolysis temperature (375–475 °C) influenced the product distribution, product composition, H2 consumption, and process carbon efficiency. The material balances ranged from 84% to 106% with an average of 91%. The organic liquid yields including C4–C6 gases ranged from 20 wt % to 24 wt %, and the gas yields were between 11 and 27 wt %. The yield of the solids varied from 8 wt % to 26 wt %. Catalyst stability was studied at 450 °C and 20.68 bar (300 psig) total pressure with 40 vol % H2 for 10 days. The organic liquid product yield (22.5 ± 1.35 wt %) and quality (2.8 ± 1 wt % O) were consistent over 10 days of experiments with the same catalyst exposed to daily hydropyrolysis, regeneration, and reduction cycles indicating stable and steady-state catalyst performance over this time period.

RTI International is developing an advanced biofuels technology that integrates a catalytic biomass pyrolysis step and a hydroprocessing step to produce infrastructure-compatible biofuels. At the current stage of development, the catalytic biomass pyrolysis process is being scaled-up in a 1 tonne per day (1 TPD) pilot plant based on a single-loop transport reactor design with continuous catalyst circulation and regeneration. The chemistry of biomass pyrolysis is manipulated by the catalyst and by controlling the pyrolysis temperature, vapor residence time, and biomass-to-catalyst ratio. The pilot unit has been successfully operated with a novel catalyst that produces a bio-crude intermediate with 24 wt% oxygen. Product yields and composition in the pilot plant are consistent with results obtained in a laboratory-scale 2.54 cm diameter bubbling fluidized bed reactor. The overall mass balance was 93%, while the carbon closure was 83%.