No abstract

5-Hydroxymethylfurfural (HMF) was catalytically converted in a bench-scale flow reactor to the oxidized derivatives 2,5-furandicarboxylic acid (FDCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-diformylfuran (DFF). Conversions and selectivities to these products depended on oxidant, pH, catalyst, and reactor operating conditions. The feasibility of producing these species in a flow reactor was demonstrated.

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Efficient synthesis of renewable fuels that will enable cost competitiveness with petroleum-derived fuels remains a grand challenge.

In the base catalyzed ethanol condensation reactions, the calcined MgO-Al 2 O 3 derived hydrotalcites used broadly as catalytic material and the calcination temperature plays a big role in determining the catalytic activity. The characteristics of the hydrotalcite material treated between catalytically relevant temperatures 450 and 800°C have been studied with respect to the physical, chemical, and structural properties and compared with catalytic activity testing. With the increasing calcination temperature, the total measured catalytic basicity dropped linearly with the calcination temperature and the total measured acidity stayed the same for all the calcination temperatures except 800°C. However, the catalyst activity testing does not show any direct correlation between the measured catalytic basicity and the catalyst activity to the ethanol condensation reaction to form 1-butanol. The highest ethanol conversion of 44 % with 1-butanol selectivity of 50 % was achieved for the 600°C calcined hydrotalcite material.

No abstract

The formation of carbonaceous deposits (coke) in zeolite pores during catalysis leads to temporary deactivation of catalyst, necessitating regeneration steps, affecting throughput, and resulting in partial permanent loss of catalytic efficiency. Yet, even to date, the coke molecule distribution is quite challenging to study with high spatial resolution from surface to bulk of the catalyst particles at a single particle level. To address this challenge we investigated the coke molecules in HZSM-5 catalyst after ethanol conversion treatment by a combination of C K-edge X-ray absorption spectroscopy (XAS), 13C Cross polarization-magic angle spinning nuclear magnetic resonance (CP-MAS NMR) spectroscopy, and atom probe tomography (APT). XAS and NMR highlighted the aromatic character of coke molecules. APT permitted the imaging of the spatial distribution of hydrocarbon molecules located within the pores of spent HZSM-5 catalyst from surface to bulk at a single particle level. 27Al NMR results and APT results indicated association of coke molecules with Al enriched regions within the spent HZSM-5 catalyst particles. The experimental results were additionally validated by a level-set–based APT field evaporation model. These results provide a new approach to investigate catalytic deactivation due to hydrocarbon coking or poisoning of zeolites at an unprecedented spatial resolution.

National Renewable Energy Laboratory (NREL) are conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). PNNL is tasked with obtaining commercially-available catalysts or preparing promising mixed alcohol catalysts and screening them in a laboratory-scale reactor system. Commercially-available catalysts and the most promising experimental catalysts are provided to NREL for testing using a slipstream from a pilot-scale biomass gasifier.After a review of the literature in 2006 and conversations at that time with companies that produce catalysts, we concluded that commercial, mixed alcohol synthesis catalysts were not available. One catalyst manufacturer did supply a modified methanol catalyst (MeOH-X) that was tested in the PNNL laboratory-scale system and then provided to NREL for further testing. PNNL also prepared and tested the behavior of 10 other catalysts that represented the distinct catalyst classes for mixed alcohol syntheses. The catalyst with the best combination of C 2 + oxygenates space time yield (STY), and selectivity was a silica-supported catalyst containing rhodium (Rh) and manganese (Mn). Based on these results, subsequent testing in 2007 and 2008 focused on the performance of the Rh-based catalyst to determine the effects of adding promoters to the Rh catalysts in addition to the Mn promoter already being used.A total of 28 tests were conducted to evaluate 22 different promoters as well as the unpromoted catalyst. The test conditions and the range of C 2 +-oxygenate STYs for these catalysts and the previously tested Rh-based catalysts are shown in Table S.1. Some of the earlier tests were conducted using a clamshell furnace to heat the reactor. However, we found that temperature control of the catalyst was difficult if not impossible to maintain for the more active catalysts, particularly when the carbon conversion was above approximately 30%. Catalysts tested with the clamshell furnace are identified in Table S.1. The clamshell furnace was replaced with a hot oil circulating system, which gave much better control for the more active catalysts, although control was still difficult for some of the more active catalysts promoted by iridium (Ir), platinum (Pt), tin (Sn), gold (Au), and molybdenum (Mo). All of these catalysts also produced significant quantities of hydrocarbon liquids, which may be related to the difficulty with temperature control (other catalysts that produced significant quantities of hydrocarbon liquids were heated with the furnace). In tests conducted with the Ir-promoted catalyst using both the furnace and the oil heating system, C 2 +-oxygenate STYs were higher when the oil-heating system was used. This finding suggests that similar improvements in the STYs may be possible for the catalysts that were only tested with the furnace.The source of the silica (SiO 2 ) was another point of interest during testing. Although all of the tests were performed with Davisil 645 SiO 2 , SiO 2 from different sources was use...