Single-Step Syngas-to-Distillates (S2D) Synthesis via Methanol and Dimethyl Ether Intermediates: Final Report

The objective of the work was to enhance price-competitive, synthesis gas (syngas)-based production of transportation fuels that are directly compatible with the existing vehicle fleet (i.e., vehicles fueled by gasoline, diesel, jet fuel, etc.). To accomplish this, modifications to the traditional methanol-to-gasoline (MTG) process were investigated. In this study, we investigated direct conversion of syngas to distillates using methanol and dimethyl ether intermediates. For this application, a Pd/ZnO/Al2O3 (PdZnAl) catalyst previously developed for methanol steam reforming was evaluated. The PdZnAl catalyst was shown to be far superior to a conventional copper-based methanol catalyst when operated at relatively high temperatures (i.e., >300°C), which is necessary for MTG-type applications. Catalytic performance was evaluated through parametric studies. Process conditions such as temperature, pressure, gas-hour-space velocity, and syngas feed ratio (i.e., hydrogen:carbon monoxide) were investigated. PdZnAl catalyst formulation also was optimized to maximize conversion and selectivity to methanol and dimethyl ether while suppressing methane formation. Thus, a PdZn/Al2O3 catalyst optimized for methanol and dimethyl ether formation was developed through combined catalytic material and process parameter exploration. However, even after compositional optimization, a significant amount of undesirable carbon dioxide was produced (formed via the water-gas-shift reaction), and some degree of methane formation could not be completely avoided. Pd/ZnO/Al2O3 used in combination with ZSM-5 was investigated for direct syngas-to-distillates conversion. High conversion was achieved as thermodynamic constraints are alleviated when methanol and dimethyl are intermediates for hydrocarbon formation. When methanol and/or dimethyl ether are products formed separately, equilibrium restrictions occur. Thermodynamic relaxation also enables the use of lower operating pressures than what would be allowed for methanol synthesis alone. Aromatic-rich hydrocarbon liquid (C5+), containing a significant amount of methylated benzenes, was produced under these conditions. However, selectivity control to liquid hydrocarbons was difficult to achieve. Carbon dioxide and methane formation was problematic. Furthermore, saturation of the olefinic intermediates formed in the zeolite, and necessary for gasoline production, occurred over PdZnAl. Thus, yield to desirable hydrocarbon liquid product was limited. Evaluation of other oxygenate-producing catalysts could possibly lead to future advances. Potential exists with discovery of other types of catalysts that suppress carbon dioxide and light hydrocarbon formation. Comparative techno-economics for a single-step syngas-to-distillates process and a more conventional MTG-type process were investigated. Results suggest operating and capital cost savings could only modestly be achieved, given future improvements to catalyst performance. Sensitivity analysis indicated that increased single-pass yield to hydrocarbon liquid is a primary need for this process to achieve cost competiveness

Editorial: The Motivations for and the Value Proposition of Sustainable Aviation Fuels

13-C-AJFE-WaSU-013This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Zhao, J.; Lee, J.Y.; Camenzind, D.; Wolcott, M.; Lewis, K.; Gillham, O. Multi-Component Resilience Assessment Framework for a Supply Chain System. Sustainability 2023, 15, 6197. https://doi.org/10.3390/su15076197Editorial on the Research Topic: The motivations for and the value proposition of sustainable aviation fuels

Modularized Production of Value-Added Products and Fuels from Distributed Waste Carbon-Rich Feedstocks

We have adapted and characterized electrolysis reactors to complement the conversion of regional- and community-scale quantities of waste into fuel or chemicals. The overall process must be able to contend with a wide range of feedstocks, must be inherently safe, and should not rely on external facilities for co-reactants or heat rejection and supply. Our current approach is based on the upgrading of bio-oil produced by the hydrothermal liquefaction (HTL) of carbon-containing waste feedstocks. HTL can convert a variety of feedstocks into a bio-oil that requires much less upgrading than the products of other ways of deconstructing biomass. We are now investigating the use of electrochemical processes for the further conversions needed to transform the bio-oil from HTL into fuel or higher value chemicals. We, and others, have shown that electrochemical reduction can offer adequate reaction rates and at least some of the necessary generality. In addition, an electrochemical reactor necessarily both oxidizes (removes electrons) on one side of the reactor and reduces (adds electrons) on the other side. Therefore, the two types of reactions could, in principle, be coupled to upgrade the bio-oil and simultaneously polish the water that is employed as a reactant and a carrier in the upstream HTL. Here, we overview a notional process, the possible conversion chemistry, and the economics of an HTL-electrochemical process. Keywords: Reducing generation and discharge of pollutants, Chemical engineerin

Inverse temperature-dependent pathway of cellulose decrystallization in trifluoroacetic acid

An unusual inverse temperature-dependent pathway was observed during cellulose decrystallization in trifluoroacetic acid (TFA). Decreasing the TFA treatment temperature accelerated the cellulose decrystallization process. It took only 100 min to completely decrystallize cellulose at 0 degrees C in TFA, a result not achieved in 48 h at 25 degrees C in the same medium. There was neither cellulose esterification nor a change of cellulose macrofibril morphology by TFA treatment at 0 degrees C. Our IR data suggest that TFA molecules are present as cyclic dimers when they penetrate into crystalline cellulose regions, transforming crystalline cellulose to amorphous cellulose. On the other hand, the rate of TFA penetration into the cellulose matrix was greatly retarded at higher temperatures where monomeric TFA prevails. At elevated temperatures, esterification of TFA monomers on the external surface of crystalline cellulose, agglomeration of cellulose macrofibrils, as well as water released from the esterification reaction, inhibit the diffusion rate of TFA into the cellulose crystalline region and decrease the TFA swelling capabilityclose141

A new route to improved glucose yields in cellulose hydrolysis

Cellulose decrystallization was nearly complete at 0 degrees C in less than 2 hours. TFA used for cellulose decrystallization was recycled via a vacuum process. The residual TFA in cellulose was diluted by adding water to form a 0.5% TFA solution and used as a catalyst for hydrolysis. The glucose yield reached 63% in 30 minutes at 175 degrees C in a batch reactor. This yield was four times higher than that from the hydrolysis of untreated cellulose using 0.5% H2SO4 under identical conditions. Alternatively, the residual TFA can be completely removed by washing with water leaving the regenerated cellulose in a highly amorphous state. Regenerated amorphous cellulose is much more reactive than untreated cellulose in hydrolysis reactionsclose11

Interactions between cellulose and N-methylmorpholine-N-oxide

Cellulose II structure was obtained when cellulose precipitated from NMMO/H2O/cellulose solution by adding excess water. The regenerated cellulose was three times more reactive than that of untreated cellulose in hydrolysis reactions. X-ray diffraction (XRD), C-13 Solid-State Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) Spectroscopy were used to investigate interactions between N-methylmorpholine-N-oxide (NMMO) and cellulose. Cellulose NMMO solid mixtures were heated to various temperatures and cooled to room temperature. The presence of cellulose in cellulose NMMO solid mixture decreased the NMMO melting point by 80-110 degrees C and hampered NMMO recrystallizing during cooling process. NMMO crystal structure collapsed between 70 and 100 degrees C in cellulose NMMO mixture and became very mobile (liquid like form). Mobile NMMO molecules transformed crystalline cellulose into amorphous cellulose. When the cellulose NMMO mixture was heated to 150 degrees C, cellulose started to replace H2O molecules that hydrogen-bonded to NMMO. Our FTIR spectra results suggest that released H2O molecules exist as both adsorbed H2O molecules on cellulose and unbound H2O molecules that are physically confined in cellulose matrix. (c) 2006 Elsevier Ltd. All rights reservedclose455

Effects of crystallinity on dilute acid hydrolysis of cellulose by cellulose ball-milling study

The dilute acid (0.05 M H2SO4) hydrolysis at 175 degrees C of samples comprised of varying fractions of crystalline (alpha-form) and amorphous cellulose was studied. The amorphous content, based on XRD and CP/MAS NMR, and the product (glucose) yield, based on HPLC, increased by as much as a factor of 3 upon ball milling. These results are interpreted in terms of a model involving mechanical disruption of crystallinity by breaking hydrogen bonds in alpha-cellulose, opening up the structure, and making more beta-1,4 glycosidic bonds readily accessible to the dilute acid. However, in parallel with hydrolysis to form liquid-phase products, there are reactions of amorphous cellulose that form solid degradation productsclose12112

Studying cellulose fiber structure by SEM, XRD, NMR and acid hydrolysis

Cotton linters were partially hydrolyzed in dilute acid and the morphology of remaining macrofibrils was studied with scanning electron microscopy (SEM) under various magnifications. The crystalline region in cellulose is composed of microfibril bundles instead of separated microfibrils. These microfibril bundles in the macrofibrils were exposed by removing amorphous cellulose on and near the surface of the macrofibers. XRD suggests that the microfibril bundles have diameters of 20-30 nm. Cellulose apparent crystallinity was not altered by hydrolysis, as indicated by XRD and NMR results. These facts suggest that amorphous cellulose in the bulk (not on the surface) is not accessible to hydrolysis and that microfibril bundles are hydrolyzed through a surface reaction process. The observed agglomerization of macrofibers could be the result of the high surface potential from the remaining nucrofibrils or acid catalyzed intermolecular surface dehydration between macrofibrils. (c) 2007 Elsevier Ltd. All rights reservedclose11814

Final Project Report Project 10749-4.2.2.1 2007-2009

This is the final report for the DOE Project 10749-4.2.2.1 for the FY2007 - FY2009 period. This report is non-proprietary, and will be submitted to DOE as a final project report. The report covers activities under the DOE Project inside CRADA 269 (Project 53231) as well as project activites outside of that CRADA (Project 56662). This is the final report that is summarized from the non-proprietary quarterlies submitted to DOE over the past 2.5 years, which in turn are summaries from the proprietary technical reporting to UOP

Final Project Report Project 10749-4.2.2.1 2007-2009

This is the final report for the DOE Project 10749-4.2.2.1 for the FY2007 - FY2009 period. This report is non-proprietary, and will be submitted to DOE as a final project report. The report covers activities under the DOE Project inside CRADA 269 (Project 53231) as well as project activites outside of that CRADA (Project 56662). This is the final report that is summarized from the non-proprietary quarterlies submitted to DOE over the past 2.5 years, which in turn are summaries from the proprietary technical reporting to UOP