Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “KHCO3”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KHCO3 by Materials Project

KHCO3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.07 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.26–1.36 Å. H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.52 Å) H–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent K1+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+, one C4+, and one H1+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to two equivalent K1+, one C4+, and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHCO3 by Materials Project

KHCO3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.77–3.05 Å. C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.59 Å) H–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to four equivalent K1+ and one C4+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to two equivalent K1+ and one H1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one C4+, and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHCO3 by Materials Project

KHCO3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.02 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.27–1.37 Å. H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.55 Å) H–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two equivalent K1+, one C4+, and one H1+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+, one C4+, and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent K1+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Synthesis of Mg–K-biochar bimetallic catalyst and its evaluation of glucose isomerization

Highly efficient isomerization of glucose to fructose is essential for valorizing cellulose fraction of biomass to value-added chemicals. This work provided an innovative method for preparing Mg-biochar and Mg–K-biochar catalysts by impregnating either MgCl 2 alone or in combination with different K compounds (Ding et al. in Bioresour Technol 341:125835, 2021, https://doi.org/10.1016/j.biortech.2021.125835 and KHCO 3 ) on cellulose-derived biochar, followed by hydrothermal carbonization and pyrolysis. Single active substance MgO existing in the 10 Mg–C could give better catalytic effect on glucose isomerization than the synergy of MgO and KCl crystalline material present in 10 Mg–KCl–C. But the catalytic effect of 10 Mg–C was decreased when the basic site of MgO was overloaded. Compared to other carbon-based metal catalysts, 10 Mg–KHCO3–C with 10 wt% MgCl 2 loading had excellent catalytic performance, which gave a higher fructose yield (36.7%) and selectivity (74.54%), and catalyzed excellent glucose conversion (53.99%) at 100 °C in 30 min. Scanning electron microscope–energy dispersive spectrometer and X-Ray diffraction revealed that the distribution of Mg 2+ and K+ in 10 Mg–KHCO 3 –C was uniform and the catalytic active substances (MgO, KCl and K2CO 3 ) were more than 10 Mg–C (only MgO). The synergy effects of MgO and K 2 CO 3 active sites enhanced the pH of reaction system and induced H 2 O ionization to form considerable OH– ions, thus easily realizing a deprotonation of glucose and effectively catalyzing the isomerization of glucose. In this study, we developed a highly efficient Mg–K-biochar bimetallic catalyst for glucose isomerization and provided an efficient method for cellulose valorization.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Cation Crossover Limits Accessible Current Densities for Zero-Gap Alkaline CO2 Reduction to Ethylene

Traditional CO2 reduction systems often fail in an alkaline environment due to the interaction of CO2 with a high-pH electrolyte, where carbonate and bicarbonate ion formation results in potassium-containing salt precipitation. The presence of the salt crystals causes a reduction in the selectivity of the electrolyzer toward CO2 conversion. Here, the critical operational variables, which elicit the salting out process, are investigated (i.e., ion transport). When the electrolyzer exceeds a critical current density, H2 evolution dominates CO2 reduction due to salt formation, which is confirmed by postmortem cross-sectional SEM-EDS of the electrode. The critical current density decreases with an increasing membrane thickness or anolyte ionic strength. Cathode salt formation is mediated by the unmitigated crossover of cations from the anolyte to the cathode across an anion exchange membrane, through which cations are imperfectly excluded. It is likely that electric field-driven migration promotes an increase in concentration of potassium across the membrane, until, at the critical current density for that electrolyzer arrangement, the concentration of potassium and bicarbonate ions exceeds the solubility limit of KHCO3, leading to salt precipitation.

CO2 reduction↗
DOE OSTI2024

Elucidating the assembly of Nanoparticle Organic Hybrid Materials (NOHMs) near an electrode interface with varying potential using Neutron Reflectivity

A critical concern regarding electrolyte formulation in an electrochemical environment is the impact of the interaction of the multiple components (i.e., supporting electrolyte or additive) with the electrode surface. Recently, liquid-like neat Nanoparticle Organic Hybrid Materials (NOHMs) have been considered as an electrolyte component to improve the transport of redox-active species to the electrode surface. However, the structure and assembly of the NOHMs near the electrode surface is unknown and could significantly impact the electrode-electrolyte interface. Hence, we have investigated the depth profile of polyetheramine (HPE) polymer and NOHM-I-HPE (nanoparticles with ionically bonded HPE polymer) in deuterated water (D2O) in the presence of two different salts (KHCO3 and ZnCl2) near two different electrode surfaces using neutron reflectometry. Moreover, the depth profile of the NOHM-I-HPE near the electrode surface in a potential has also been studied with in-situ reflectivity experiments. Our results indicate that a change in the chemical structure/hydrophilicity of the electrode surface does not significantly impact the ordering of HPE polymer or NOHM-I-HPE near the surface. Here, this study also indicates that the NOHM-I-HPE particles form a clear layer near the electrode surface immediately above an adsorbed layer of free polymer on the electrode surface. The addition of salt does not impact the layering of NOHM-I-HPE, though it does alter the conformation of the polymer grafted to the nanoparticle surface and free polymer sequestered near the surface. Finally, the application of negative potential results in an increased amount of free polymer near the electrode surface. Correlating the depth profile of free polymer and NOHM-I-HPE particles with the electrochemical performance indicates that this assembly of free polymer near the electrode surface in NOHM-I-HPE solutions contributes to the higher current density of the system. Therefore, this holistic study offers insight into the importance of the assembly of NOHM-I-HPE electrolyte and free polymer near the electrode surface in an electrochemical milieu on its performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗