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Hoffman, James S.

Publications and source records attributed to Hoffman, James S..

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Amino acids react with carbon dioxide (CO2) and form nanofibers and nanoflowers

A method for capturing CO2 comprising dissolving at least one pure amino acid (AA) in water without the use of a catalyst for establishing protonation of an amino group of the amino acid, adding at least one base solution to the amino acid and water solution to deprotonate the protonated amino group of the amino acid and forming an amino acid-XOH—H2O wherein X is sodium or potassium, and subjecting CO2 to the amino acid-XOH—H2O to form new nanomaterials is provided. A regenerable nanofiber is disclosed comprising a NaHCO3 nanofiber, a KHCO3 nanofiber, or an amino acid nanofiber made from subjecting a CO2 gas to an amino acid aqueous solvent. Preferably, the amino acid aqueous solvent is one or more of a Gly-NaOH—H2O, an Ala-NaOH—H2O, a Phe-NaOH—H2O, a Gly-KOH—H2O, an Ala-KOH—H2O, and a Phe-KOH—H2O.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Polymers of Intrinsic Microporosity Chemical Sorbents Utilizing Primary Amine Appendance Through Acid–Base and Hydrogen-Bonding Interactions

In this work, we introduce novel chemical sorbents based on polymers with intrinsic microporosity (PIMs). For the first time, alkylamines were incorporated in PIMs through an acid–base interaction to create a chemisorbent. The amine-appended PIMs not only showed a nearly four-fold enhancement in CO 2 loading capacity (36.4 cc/g at 0.15 bar and 298 K) and very high CO 2 /N 2 selectivity compared to neat PIM -1 but moreover proved to have stable performance when cycled between adsorption and desorption isotherms under both dry and humid conditions that are typical for postcombustion CO 2 capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO 2 Capture

An amine sorbent, prepared by impregnation of polyethyleneimine on silica, was tested for steam stability. The stability of the sorbent was investigated in a fixed bed reactor using multiple steam cycles of 90 vol % H 2 O/He at 105 °C, and the gas effluent was monitored with a mass spectrometer. CO 2 uptake of sorbent was found to decrease with repeated exposure to steam. Characterization of the spent sorbent using N 2 physisorption, SEM, and thermogravimetric analysis (TGA) showed that the decrease in CO 2 loading can possibly be attributed to a reagglomeration of the amine in the pores of the silica. No support effect was found in this study. The commercial SiO 2 used, Cariact G10, was found to be stable under the conditions used. While it was found that subjecting the sorbent to several steam cycles decreased its CO 2 uptake, a continuous exposure of the sorbent to steam did not have a significant performance impact. Finally, a silanated sorbent, consisting of a mixture of PEI and aminopropyl-triethoxysilane on SiO 2 support, was also investigated for steam stability. Similarly to the nonsilanated sorbent, the CO 2 loading of this sorbent decreased upon steam exposure, although a mechanism for this change has not been postulated at this time.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Packed-Bed Reactor Study of NETL Sample 196c for the Removal of Carbon Dioxide from Simulated Flue Gas Mixture

An amine-based solid sorbent process to remove CO 2 from flue gas has been investigated. The sorbent consists of polyethylenimine (PEI) immobilized onto silica (SiO 2 ) support. Experiments were conducted in a packed-bed reactor and exit gas composition was monitored using mass spectrometry. The effects of feed gas composition (CO 2 and H 2 O), temperature, and simulated steam regeneration were examined for both the silica support as well as the PEI-based sorbent. The artifact of the empty reactor was also quantified. Sorbent CO 2 capacity loading was compared to thermogravimetric (TGA) results to further characterize adsorption isotherms and better define CO 2 working capacity. Sorbent stability was monitored by periodically repeating baseline conditions throughout the parametric testing and replacing with fresh sorbent as needed. The concept of the Basic Immobilized Amine Sorbent (BIAS) Process using this sorbent within a system where sorbent continuously flows between the absorber and regenerator was introduced. The basic tenet is to manipulate or control the level of moisture on the bent as it travels around the sorbent circulation path between absorption and regeneration stages to minimize its effect on regeneration heat duty.

58 GEOSCIENCES↗