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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Slippery liquid infused porous surface (SLIPS) condensers for high efficiency air gap membrane distillation

Abstract To address growing water scarcity, we must improve the energy efficiency of thermal desalination technologies such as air gap membrane distillation. However, promising functional materials such as slippery liquid infused porous surfaces have not yet implemented for any desalination technology. Here, we fabricate and test slippery liquid infused porous surfaces (using Krytox 16,256 lubricant and CuO nanostructures) in an air gap membrane distillation apparatus. System-level transport models, validated by experimental data, establish a framework for improving performance through enhanced condensation surfaces. Results are obtained across a range of temperatures (50–80 °C), salinities (5–105 g/kg), and module lengths. We find that small air gap thickness and efficient droplet shedding significantly improves performance. The CuO Krytox process achieves these with a conductive-self-limiting coating, high nanostructure rugosity, strong covalent and metallic bonding, high hydrophobicity, minimal droplet pinning sites, and ultra-low contact angle hysteresis. The greatest efficiency enhancement from SLIPS is derived from the improved droplet shedding, which allows for reduced gap sizes without flooding, and is further augmented by the increased permeate flux.

Yogi, Yashwant S.↗
DOE OSTI2022

Outgassing of casted and 3D printed silicones

Outgassing of 3D printed and casted silica-filled silicones was studied using a standard ASTM E-595 procedure and a modified Soreq’s method that allows very sensitive measurements of the outgassing kinetics even at low temperatures, 20 – 50 °C. We studied three different silica-filled silicones, non-porous cased M9787, and 3D printed LL50 and 40P materials. The present report shows that vacuum outgassing products of polysiloxane-based materials include multiple species. In addition to chemisorbed and physisorbed water outgassing, previously studied by TPD, polymer fragments of varying sizes evaporate as well. The chemical composition of the condensable volatile species collected on a Germanium substrate, was analyzed by FTIR. It was shown that all studied materials produce mostly PDMS-based outgassing products that form stable droplet-like structure on the Ge substrate. The highest amount of the condensable volatile species was measured for LL50. Isothermal TGA in nitrogen atmosphere of the LL50 material was compared to the standard vacuum outgassing. The results of TGA showed lower mass loss and higher water regain. The kinetics of the outgassing at relatively low temperatures of 20, 30 and 50 °C was studied using Thermoelectric Quartz Crystal Microbalance (TQCM). The TQCM surface was held at -10 °C to enhance condensation of the outgassed moisture. The analysis presented here, when combined with the extensive previous work on moisture outgassing, provides a better understanding of the aging mechanism of polysiloxane-based materials. In this work we show that outgassing techniques, usually applied for qualification of polymers for space-related applications, may be used as a complementary method to study thermal degradation and aging of silica-based silicones. Our results indicate that the long-term degradation mechanics and thermal degradation products depend primarily on the chemical composition of silicone-based material and only slightly affected by the manufacturing process. Surprisingly, the surface-to-volume ratio of the 3D printed vs. casted/molded materials showed only minor effect on the outgassing kinetic parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Silicon alloying enhances fast heating rate combustion of aluminum particles

Alloys and composites of aluminum (Al) have shown promise in regulating and enhancing particle combustion for energy generation applications. Recent work on aluminum-silicon (Al-Si) spherical alloy particles has shown improved combustion at low heating rates through enhanced diffusion accompanying a lower melting temperature. This study extends reactivity analysis to higher heating rates, comparing oxidation of Al-Si with Al. Flame speeds of Al-Si powder mixed with molybdenum trioxide (MoO 3 ) powder (Al-Si+MoO 3 ) exhibited a faster transition to steady propagation relative to Al+MoO 3 . Bomb calorimetry experiments revealed up to 5.8% greater early temperature rise for Al-Si powder. Rapid steady propagation for Al-Si mixture and faster temperature rise for Al-Si particles were attributed to accelerated kinetics evidenced in thermal equilibrium analysis of the mixtures using a differential scanning calorimeter (DSC). Larger DSC exotherms in the early stages of oxidation (i.e., 480–720 °C) correlated with early heat release and promoted steady flame propagation for Al-Si+MoO 3 compared with Al+MoO 3 . Furthermore, in multiple heating rate DSC studies, Al-Si+MoO 3 ignited at a lower heating rate (i.e., 15 ⁰C/min) than Al+MoO 3 (i.e., 20 ⁰C/min). Both mixtures ignited at temperatures less than 625 °C which is above the melting temperature of Al-Si (574 °C) and below Al (659 °C). Thus, alloy particle fuels with enhanced diffusion-controlled kinetics promote steady flame propagation and show promise for energy generation applications. This is especially promising for technologies driven by enhanced condensed phase combustion such as some propellant additives or applications dependent on reliable burn rates such as pyrotechnic time delay formulations and primers.

36 MATERIALS SCIENCE↗
DOE OSTI2022

NUMERICAL INVESTIGATION OF AIR DEHUMIDIFICATION THROUGH WATER DROPLETS DIELECTROPHORESIS

This paper numerically investigated the dehumidification of moist airflow in a converging rectangular duct with electrically enhanced condensation. The aim was to develop a condensation model that predicted water vapor condensation by employing the dielectrophoresis principle. The charged droplets were injected into the computational domain to produce a gradient electric field. The dielectrophoretic interaction between the droplets and vapor molecules of the humid air resulted in local water vapor condensation at the vapor and liquid droplet interface. This phenomenon is described in detail in this paper. A hybrid Eulerian-Lagrangian solver SprayFoam was developed based on OpenFOAM® to simulate condensation in two-phase gas-liquid mixtures. The following developments were made based on the standard compressible multiphase flow solver SprayFoam in OpenFOAM®: (1) Eulerian solver for gas phase (2) multi-component species transport, and (3) Lagrangian solver for gas-droplet two-phase flows and sub-models for liquid droplets. The newly developed numerical model was experimentally validated with data from a series of tests conducted in the authors' laboratory. The results showed that the simulations followed the same trends as the data, and the model predicted the condensation due to the electro-spray injection process in the air stream. The injected water droplets, which are electrically charged to their Rayleigh limits, increased in size while wiping out the humidity from the air. The simulations indicated that the dehumidification was about 1% for 0.5 cubic feet per minute airflow rate. Scaling up to larger flows is a future follow-up work.

Yel Mahi, *Maliha↗
DOE OSTI2023

Examining the vertical heterogeneity of aerosols over the Southern Great Plains

Abstract. Atmospheric aerosols affect the global energy budget by scattering and absorbing sunlight (direct effects) and by changing the microphysical structure, lifetime, and coverage of clouds (indirect effects). Both aerosol direct and indirect effects are affected by the vertical distribution of aerosols in the atmosphere, which is further influenced by a range of processes, such as aerosol dynamics, long-range transport, and entrainment. However, many observations of these processes are based on ground measurements, limiting our ability to understand the vertical distribution of aerosols and simulate their impact on clouds and climate. In this work, we examined the vertical heterogeneity of aerosols over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) using data collected from the Holistic Interactions of Shallow Clouds, Aerosols and Land Ecosystems (HI-SCALE) campaign. The vertical profiles of meteorological and aerosol physiochemical properties up to 2500 m above are examined based on the 38 flights conducted during the HI-SCALE campaign. The aerosol properties over the SGP show strong vertical heterogeneity and seasonal variabilities. The aerosol concentrations at the surface are the highest due to strong emissions at ground level. In general, the mode diameter of aerosols during summer (∼ 100 nm) is larger than that during spring (∼ 30 nm), a result of enhanced condensational growth due to enriched volatile organic compounds in summer. The concentration of aerosols below 30 nm in the boundary layer (BL) (e.g., below 1000 m) during spring is higher than that during summer, a result of the stronger new particle formation (NPF) events due to the reduced condensation sink in spring. In the BL, the size of the aerosols gradually increases with altitude due to condensational growth and cloud processing. However, the chemical composition of the aerosols remained similar, with organics and sulfates representing 59.8 ± 2.2 % and 22.7 ± 2.1 %, respectively, of the total mass in the BL. Through the vertical profiles of aerosol properties, we observed NPF events in the upper BL during 7 out of 38 research flights, where the newly formed particles continue to grow as they are mixed down to the surface. There is also an indication that deep convection brings aerosols from the free troposphere (FT) to the surface, where they grow to contribute to the cloud condensation nuclei (CCN). Overall, the vertical heterogeneity of aerosols over the SGP is influenced by aerosol dynamics (new particle formation, growth, and cloud processing) and transport processes (mixing in the BL, long-range transport, entrainment, and convective downward transport). Case studies showing the influence of these factors are discussed.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2015

Daily Global Mapping of Mars Ozone Column Abundances with MARCI UV Band Imaging

Since November of 2006, The Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) has obtained multiple-filter daily global images of Mars centered upon a local time (LT) of 3 pm. Ultraviolet imaging bands placed within (260 nm) and longward (320 nm) of Hartley band (240-300 nm) ozone (O3) absorption support retrievals of atmospheric ozone columns, with detection limits (approximately 1 micrometer-atm) appropriate to mapping elevated O3 abundances at low latitudes around Mars aphelion, and over mid-to-high latitudes during fall/winter/spring seasons. MARCI O3 maps for these regions reveal the detailed spatial (approximately 1 deg lat/long, for 8 x 8 pixel binned resolution) and temporal (daily, with substantial LT coverage at pole) behaviors of water vapor saturation conditions that force large variations in water vapor photolysis products (HOx-OH, HO2, and H) responsible for the catalytic destruction of O3 in the Mars atmosphere. A detailed description of the MARCI O3 data set, including measurement and retrieval characteristics, is provided in conjunction with comparisons to Mars Express SPICAM ozone measurements (Perrier, S. et al. [2006]. J. Geophys. Res. (Planets) 111) and LMD GCM simulated O3 abundances (Lefevre, F. [2004]. J. Geophys. Res. (Planets) 109). Presented aspects of the MARCI ozone mapping data set include aphelion increases in low latitude O3, dynamically evolving high latitude O3 maxima associated with planetary waves and weather fronts during northern early spring, and distinctive winter/spring O3 and CO increases within the Hellas Basin associated with transport of condensation enhanced south polar air mass. Comparisons of coincident MARCI measurements and LMD simulations for ice cloud and O3 columns are considered in the context of potential heterogeneous photochemical processes (Lefevre, F. [2008]. Nature 454, 971-975), which are not strongly evidenced in the MARCI observations. Modest interannual variations are exhibited, most notably a 20% reduction in aphelion low latitude O3 columns following the 2007 perihelic global dust storm.

Clancy, R. Todd↗
NASA NTRS2022

Test data analysis of the thermodynamic vent system-augmented top spray injector liquid nitrogen transfer experiments

Traditionally, a cryogenic tank must be pre-chilled to some “target” temperature before the main vent valve can be closed to attempt a non-vented fill (NVF) of cryogenic liquid propellant. This methodology is particularly attractive for performing in-space transfer of cryogens due to the unknown location of the liquid/vapor interface in microgravity and the high likelihood of venting liquid if the vent valve is opened during transfer. This paper presents in-depth test data analysis of a Thermodynamic Vent System (TVS) augmented injector used for cryogenic tank chilldown and fill experiments of a thin-walled Titanium tank. Eight tests were conducted using liquid nitrogen across a range of inlet conditions and boundary conditions, and three different chilldown/fill methods. For four of the tests, the injector sprays liquid into the tank as normal, but also uses a TVS heat exchanger to cool the metallic injector itself as well as the main incoming liquid stream. Results show that using the TVS augmented injector simplifies transfer operation via enhanced condensation at the injector surface at the cost of sacrificing only a small amount of propellant.

No-vent Fill↗
DOE OSTI2021

Capillary-driven Condensation for Heat Transfer Enhancement in Steam Power Plants

A novel condensation method was developed to enhance the efficiency of steam power plants. The method consists of a hierarchical structure on the surface of condenser tubes consisting of a wicking structure overlaid with a porous hydrophobic membrane. The project is divided into two main efforts. First, a structure with highly defined geometry was made utilizing microfabrication on silicon. This structure helped us elucidate the physics of steam condensation at the surface, more easily model the heat transfer coefficient, and demonstrate the first proof-of-concept for our proposed condensation approach. The structures on silicon achieved a heat transfer coefficient ~ 240% higher than the theoretical filmwise value at the same operating condition. Second, the method is explored for scalability by fabricating surfaces with industrial class materials followed by heat transfer measurements on flat surfaces. An HTC enhancement of 50% over the experimental filmwise value was achieved on hierarchical copper surfaces made of commercially available copper foams and meshes, showing the potential of achieving heat transfer enhancement using low cost and scalable materials. Scalable fabrication of the hydrophobic membrane and the porous copper wick were also investigated. Our heat and mass transfer model predicts a > 5x heat transfer enhancement on a scalable version of capillary driven condenser made of membrane covered porous copper. The results demonstrate the promise of capillary-driven condensation surfaces for heat transfer applications.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2022

Novel solid-infused durable nonwetting surfaces for sustained condensation heat transfer enhancement

Here, in this article, we report novel nonwetting solid-infused surfaces that are easily fabricated using industrially widely adopted methods such as chemical etching or electrodeposition and exhibit sustained dropwise condensation performance durably than superhydrophobic and lubricant-infused surfaces. Solid-infused surfaces demonstrate fourfold larger condensation heat transfer coefficient and 25% better condensation effectiveness when compared to superhydrophobic surface and conventional filmwise condensation. Although the condensation heat transfer coefficient of lubricant-infused surface initially matches that of solid-infused surface, it is shown through durability studies that the wettability characteristic that underpins the performance of lubricant-infused surfaces degrades quickly with time as the lubricant depletes and lubricant-infused surface transitions to superhydrophobic surface. Solid-infused surface, on the other hand, retains its steadfast superior dropwise condensation effectiveness in the long run, overcoming the challenges of droplet pinning, surface inundation, cloaking, and lubricant depletion that eventually deteriorate condensation on conventional nonwetting superhydrophobic and lubricant-infused surfaces.

42 ENGINEERING↗
DOE OSTI2023

Enhancements in Cloud Condensation Nuclei Activity From Turbulent Fluctuations in Supersaturation

Abstract The effect of aerosols on the properties of clouds is a large source of uncertainty in predictions of weather and climate. These aerosol‐cloud interactions depend critically on the ability of aerosol particles to form cloud droplets. A challenge in modeling aerosol‐cloud interactions is the representation of interactions between turbulence and cloud microphysics. Turbulent mixing leads to small‐scale fluctuations in water vapor and temperature that are unresolved in large‐scale atmospheric models. To quantify the impact of turbulent fluctuations on cloud condensation nuclei (CCN) activation, we used a high‐resolution Large Eddy Simulation of a convective cloud chamber to drive particle‐based cloud microphysics simulations. We show small‐scale fluctuations strongly impact CCN activity. Once activated, the relatively long timescales of evaporation compared to fluctuations causes droplets to persist in subsaturated regions, which further increases droplet concentrations.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1986

Numerical simulations of a siphon mechanism for quiescent prominence formation

Quiescent prominences represent a significant challenge to our understanding of the flow of mass and energy in the outer layers of the solar atmosphere. A small number of quiescent prominences contain as much mass as the entire corona (Athay, 1976). The problem then is how to get that much material into the relatively small volume of a prominence and maintain it at a temperature of 10,000 K in close proximity to material at one million K. The thermal insulation to conduction provided by the magnetic field explains the disparate temperatures. The mass source problem is less well understood. One method for supplying mass to the prominence is to siphon it from the chromosphere. The siphon mechanism begins with a magnetic loop that evolves into a configuration with a gravitational well, such as that described by Kippenhahn and Schluter (1957). This could be formed, for example, by a twist in the magnetic field. A gravitational well could also be formed by a condensation induced sag in the field. This could further enhance the condensation process. Once this well has formed, or as it is forming, the material in the well area of the loop must cool and condense to the point where radiative losses exceed any heat input. Additional material must also flow into the well from the underlying chromosphere to supply the mass required to form the prominence. One example from a series of numerical simulations that were performed to study the formation of quiescent prominences is presented.

Poland, A. I.↗
DOE OSTI2022

Thermodynamic Model and Initial Experimental Investigation of Air Dehumidification through Electrically Charged Vapor Capturing Electrostatic Droplets

The removal of water vapor from the air to reduce relative humidity is a well known indoor environmental comfort requirement. Common dehumidification approaches require a substantial amount of energy and usually involve the cooling of atmospheric humid air below its dew point or the use of absorbent/adsorbent materials to extract water vapor out of the air. More recently, researchers investigated the effect of electrostatic forces for enhancing water vapor condensation with the goal to reduce the energy consumption associated with dehumidification. However, the studies are limited, and there is a lack of correlations that can predict the dehumidification rate. In this thesis, a broad theoretical investigation to study the electrostatically enhanced condensation processes was carried out. These processes consist of the use of highly charged particles, preferably highly charged water droplets to attract polar water vapor molecules to their surfaces and promote condensation, a phenomenon known as dielectrophoresis. The electrical charge promotes the reduction of the vapor pressure on the droplets' surface with respect to the saturated pressure predicted by the Kelvin equation on curved surfaces and, consequently, the equilibrium between evaporation and condensation is shifted towards condensation. This investigation resulted in the development of a thermodynamics model, which was able to predict an effective size range of the charged droplets for optimal dehumidification, under ideal conditions. The range resulted in about 2 to 4 m in diameter, while the electrical charge was kept to the maximum limit predicted by the Rayleigh model. A sensitivity analysis on the variation of the size and the charge of the charged droplets was also performed. In terms of dehumidification rates, when six electrospray heads, i.e. the maximum number of heads tested in the experimental campaign, were considered, the model predicted very limited rates, way lower than the target of this research, i.e. a dehumidification rate in terms of relative humidity of 5 % with an air flow rate of 5 cfm. While ways to increase this rate existed, their implementation proved difficult for this initial investigation. According to the requirements predicted by the model, the use of electrosprays appeared the most suitable solution for the production of small but highly charged droplets. The electrospray features and operational modes were studied in detail and an electrospray assembly was designed to be tested in this initial experimental investigation. For this initial investigation, an experimental system was designed and built to validate the thermodynamics model and with the goal to achieve a dehumidification rate of 5 % in terms of relative humidity with an air flow rate of 5 cfm. The experimental system consisted of a wind tunnel test apparatus, dew point sensors, thermocouples for temperature measurements, pressure sensors and other devices. The experimental system was equipped with a computerized data acquisition and storage system. The system was suitable to evaluate the air water content differential before and after the test section where the electrospray heads were installed. The air water content differential was evaluated in terms of the ∆ω/ω_1 ratio, to eliminate the dependence on the dry bulb temperature along the test apparatus. This work presented initial experimental data for electrostatically enhanced dehumidification processes. Working parameters, such as air and water flow rates, high voltage potentials and polarity, deionized water types with different electrical conductivity, were varied to find the best combination for an improved dehumidification. With the set up used and the conditions considered, it was never possible to achieve a 5 % dehumidification rate with 5 cfm. In general, the dehumidification rate was always limited and lower than 1 % for all the air flow rates considered and mainly within the uncertainty of the dew point sensors. These results confirmed the already limited predictions of the thermodynamics model, for ideal conditions and the interesting and promising results obtained in some experimental investigations available in the open literature were not achievable in this thesis. The more probable reasons were the higher air flow rates considered and the complete absence of the use of cooling power, which was mainly implemented to facilitate the vapor condensation.

Morcelli, Stefano↗
DOE OSTI2021

Analysis of Electro-static Assisted Air Dehumidification

The removal of water vapor from the air to reduce relative humidity is a well-known indoor environmental comfort requirement. Common dehumidification approaches require a substantial amount of energy and usually involve the cooling of atmospheric humid air below its dew point or the use of absorbent/adsorbent materials to extract water vapor out of the air. More recently, researchers investigated the effect of electrostatic forces for enhancing water vapor condensation. However, the studies are limited, and there is a lack of correlations that can predict the dehumidification rate. Also, the findings from the literature focused mainly on small flow rates on the order of one to two cfm. Electrically-enhanced condensation consists of the use of highly charged particles, preferably highly charged water droplets, that attract polar water vapor molecules to their surfaces and promote condensation, a phenomenon known as dielectrophoresis. An effect of the electric charge is the reduction of the vapor pressure on the droplets' surface with respect to the saturated pressure predicted by the Kelvin equation. Consequently, the equilibrium between evaporation and condensation is shifted towards condensation. Following the application of the modified Kelvin-Thomson theory, we developed a preliminary physics-based model to predict an effective size range of the charged droplets for optimal dehumidification. The range resulted in about 2 to 4 μm in diameter, under few simplifying assumptions. The effect of the size and the charge of the electrosprayed droplets on the overall dehumidification rate was briefly discussed. The use of electrosprays to produce small but highly charged droplets was broadly discussed in this paper. The cone-jet mode was identified as the most suitable electrospray operational mode, and it generated droplets of small size and high electrical charge. The cone-jet stability was also analyzed in detail. The preliminary data of the present work and the model results indicated that several electrospray heads were required to achieve a 5% dehumidification rate for airflow rates of about 5 cfm.

Morcelli, Stefano↗
DOE OSTI2021

Analysis of New Data of Electro-static Assisted Air Dehumidification Processes

The removal of water vapor from the air to reduce relative humidity is a well-known indoor environmental comfort requirement. Common dehumidification approaches require a substantial amount of energy and usually involve the cooling of atmospheric humid air below its dew point or the use of absorbent/adsorbent materials to extract water vapor out of the air. More recently, researchers investigated the effect of electrostatic forces for enhancing water vapor condensation. However, the studies are limited, and there is a lack of correlations that can predict the dehumidification rate. Also, the findings from the literature focused mainly on small flow rates on the order of one to two cfm. Electrically-enhanced condensation consists of the use of highly charged particles, preferably highly charged water droplets, that attract polar water vapor molecules to their surfaces and promote condensation, a phenomenon known as dielectrophoresis. An effect of the electric charge is the reduction of the vapor pressure on the droplets' surface with respect to the saturated pressure predicted by the Kelvin equation. Consequently, the equilibrium between evaporation and condensation is shifted towards condensation. Following the application of the modified Kelvin-Thomson theory, we developed a preliminary physics-based model to predict an effective size range of the charged droplets for optimal dehumidification. The range resulted in about 2 to 4 m in diameter, under few simplifying assumptions. The effect of the size and the charge of the electrosprayed droplets on the overall dehumidification rate was briefly discussed. The use of electrosprays to produce small but highly charged droplets was broadly discussed in this paper. The cone-jet mode was identified as the most suitable electrospray operational mode, and it generated droplets of small size and high electrical charge. The cone-jet stability was also analyzed in detail. The preliminary data of the present work and the model results indicated that several electrospray heads were required to achieve a 5% dehumidification rate for airflow rates of about 5 cfm.

Morcelli, Stefano↗
NASA NTRS1995

Tropospheric Lapse Rate and Methane on Titan

We have reanalyzed the Voyager radio occultation data for Titan with two alternative approaches to methane condensation. In one approach, methane condensation is enhanced by the presence of nitrogen. In the other approach, methane condensation does not occur. As pointed out by Thompson, nitrogen lowers the condensation level for a methane/nitrogen Mixture and we find that the upper limit on surface relative humidity of methane obtained from the Voyager occultation data is lowered from 0.7 to 0.6. However, 140% supersaturation of methane in the troposphere, suggested by Courtin et al., allows all surface humidities to be consistent with the Voyager occultation data and the upper limit is set by other considerations. We conclude that if supersaturation is not included then the surface relative humidity of methane is between 0.08 and 0.6, with values close to 0.6 indicated. If supersaturation is included then the surface relative humidity of methane is between 0.08 and 0.85, again, with values close to 0.6 indicated. The tropospheric lapse rate on Titan appears to be determined by radiative equilibrium. It is everywhere stable against dry convection but is unstable to moist convection. This is consistent with a supersaturated atmosphere in which condensation - and hence moist convection - is inhibited. The absence of dry convection in the troposphere of Titan can be explained by a simple grey model which shows that the radiative profile of any gas for which the ratio of the gas constant to the specific heat at constant pressure is greater than 0.25 never becomes unstable to dry convection.

McKay, C. P.↗
DOE OSTI2020

Pyrolysis Vapor and Bio-Oil Preconditioning via Ex Situ Hydrodeoxygenation and Alkylation Using a Heteropolyacid Catalyst

Ex situ catalytic preconditioning of biomass pyrolysis vapors (partial deoxygenation) has the potential for both reducing the oxygen content and beneficially influencing the oxygen speciation of condense bio-oils for enhancement of downstream condensed phase upgrading processes. Here, condensed phase upgrading processes may refer to both coprocessing and hydroprocessing with vacuum gas-oil (VGO). Reduction of oxygen content to produce bio-oils with greater hydrophobicity can enhance VGO-solubility while tailoring of oxygen speciation by removal of reactive carbonyls (e.g., acetic acid) can lessen catalytic deactivation via coking reactions. 1,2 Furthermore, enhanced VGO-solubility and reduced coking leads to greater biogenic carbon incorporation in end-products from condensed phase upgrading processes. By leveraging the hydrodeoxygenation and alkylation activity of a titania-supported molybdenum-heteropolyacid (Mo-HPA/TiO2) catalyst, pyrolysis vapors and resulting condensed bio-oils were effectively preconditioned for downstream upgrading. 3 Data regarding the use of Mo-HPA/TiO2 for pyrolysis vapor preconditioning will be presented on, including method of employment, catalyst characterization, and impacts on bio-oil in relation to downstream condensed phase upgrading processes. Our approach is to: Compare Mo-HPA/TiO2 product distribution to HZSM-5; Investigate Mo-HPA/TiO2 regeneration and characterize changes in acid site character; Assess product differences in terms of enhanced VGO-solubility.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗