Hydrogen Storage at Ambient Temperature by the Spillover Mechanism

The goal of this project was to develop new nanostructured sorbent materials, using the hydrogen spillover mechanism that could meet the DOE 2010 system targets for on-board vehicle hydrogen storage. Hydrogen spillover may be broadly defined as the transport (i.e., via surface diffusion) of dissociated hydrogen adsorbed or formed on a first surface onto another surface. The first surface is typically a metal (that dissociates H2) and the second surface is typically the support on which the metal is doped. Hydrogen spillover is a well documented phenomenon in the catalysis literature, and has been known in the catalysis community for over four decades, although it is still not well understood.1, 2 Much evidence has been shown in the literature on its roles played in catalytic reactions. Very little has been studied on hydrogen storage by spillover at ambient temperature. However, it is also known to occur at such temperature, e.g., direct evidence has been shown for spillover on commercial fuel-cell, highly dispersed Pt/C, Ru/C and PtRu/C catalysts by inelastic neutron scattering.3 To exploit spillover for storage, among the key questions are whether spillover is reversible at ambient temperature and if the adsorption (refill) and desorption rates at ambient temperature are fast enough for automotive applications. In this project, we explored new sorbents by using a transition metal (e.g., Pt, Ru, Pd and Ni) as the H2 dissociation source and sorbents as the hydrogen receptor. The receptors included superactivated carbons (AX-21 and Maxsorb), metal organic frameworks (MOFs) and zeolites. Different metal doping methods have been used successfully to achieve high metal dispersion thereby allowing significant spillover enhancements, as well as a bridging technique used for bridging to MOFs. Among the metals tested, Pt is the hardest to achieve high metal dispersion (and consequently spillover) while Ru is the easiest to disperse. By properly dispersing Pt on superactivated carbons (by following detailed doping and activation conditions given in our publications, e.g., Ref. 12), the storage capacities are increased two-fold (doubled) while slightly more than doubled by Ru doping. The bridging technique remains highly empirical and sample-to-sample consistency is difficult to achieve; however, significant enhancements by spillover can be achieved if the synthesis and pretreatment are done properly. Pitfalls in sample syntheses for both metal doped and bridged sorbents are pointed out in the report; deviations from the synthesis and pretreatment conditions will lead to diminished or no spillover effects. Due to the high bulk densities of zeolites, metal doped zeolites are shown to be most promising for achieving high volumetric storage capacities by spillover. Kinetics of both spillover and reverse spillover (i.e., desorption) at ambient temperature are also studied. This report summarizes the progress made in the project

Mixed‐cation LiCa‐LSX zeolite with minimum lithium for air separation

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141696/1/aic16032.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141696/2/aic16032_am.pd

Fe-ZSM-5 for Selective Catalytic Reduction of NO with NH3: A Comparative Study of Different Preparation Techniques

Fe-ZSM-5 are prepared by using four different techniques: conventional aqueous ion-exchange (CA), improved aqueous ion-exchange (IA), solid-state ion-exchange (SS) and chemical vapor ion-exchange (CV). All of the catalysts show very high activities for selective catalytic reduction (SCR) of NO with ammonia. However, the activities are different and follow the sequence of Fe-ZSM-5 (IA) > Fe-ZSM-5 (CA), Fe-ZSM-5 (SS) > Fe-ZSM-5 (CV). ESR results indicate that Fe 3+ ions with tetrahedral coordination are the active sites for the SCR reaction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44258/1/10562_2004_Article_341671.pd

Pt/MCM-41 catalyst for selective catalytic reduction of nitric oxide with hydrocarbons in the presence of excess oxygen

First results are reported on the use of MCM-41 mesoporous molecular sieve as the support for Pt for the selective catalytic reduction of NO by hydrocarbons in the presence of O 2 . MCM-41 provided the highest specific NO reduction rates for Pt as compared with all other supports reported in the literature, i.e., Al 2 O 3 , SiO 2 and ZSM-5.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44252/1/10562_2004_Article_326634.pd

Acid- and base-treated Fe 3+ -TiO 2 -pillared clays for selective catalytic reduction of NO by NH 3

Fe 3+ -ion-exchanged delaminated pillared clays (PILCs) have been found previously to be more active than the vanadia-based catalysts for selective catalytic reduction (SCR) of NO by NH 3 . The effects of acid treatment of the clay (before pillaring) and base treatments of the TiO 2 -PILC (before ion exchange) on the activities of the Fe–TiO 2 -PILC catalysts were studied. It was found that the acid treatment increased the activity (by 33%), but the base treatments decreased the activity (although they increased the cation exchange capacity of the pillared clay and, hence, the Fe content). The activities of the catalysts were directly related to their surface Brønsted acidities as identified by FT-IR of chemisorbed NH 3 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44255/1/10562_2004_Article_326912.pd

Concentration profile for linear driving force model for diffusion in a particle

No Abstrast.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34236/1/690450118_ftp.pd

Corrected HorvÁth-Kawazoe equations for pore-size distribution

The HorvÁth-Kawazoe (HK) model is a widely used method for determining pore-size distribution in a microporous material from a single adsorption isotherm. The original model, however, suffers from conceptual flaws. The total interaction energy of the adsorbate is underestimated since the adsorbate-adsorbate interaction is incorrecty calculated. New corrected HK models proposed here for three pore geometries (slit, cylindrical, and spherical) can overcome these defects. Two other improvements have also been made in the new models. These assume that a filled micropore is composed of layers of adsorbate molecules which interact only with the molecular layers in the immediate vicinity. A better estimate of adsorbate-adsorbate-adsorbent interaction is obtained by utilizing actual distances between interacting molecules. The average interaction energy is calculated by a population-weighted average of the energy potential of the layers rather than by integration. This average potential approaches a nonzero value at large pore size, unlike that in the original model. Pore-size distributions predicted by the corrected HK models agreed significantly better with crystallographic data compared to the original model for both microporous and mesoporous sorbents.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34240/1/690460408_ftp.pd

Quantum Optical Systems for the Implementation of Quantum Information Processing

We review the field of Quantum Optical Information from elementary considerations through to quantum computation schemes. We illustrate our discussion with descriptions of experimental demonstrations of key communication and processing tasks from the last decade and also look forward to the key results likely in the next decade. We examine both discrete (single photon) type processing as well as those which employ continuous variable manipulations. The mathematical formalism is kept to the minimum needed to understand the key theoretical and experimental results

Adsorption and Ultrasound-Assisted Sorbent Regeneration

This work was conducted for the department of Energy. In this work, we developed a class of new sorbents that were highly sulfur selective and had high sulfur capacities. The study consisted of two sections. Development of the new sorbents is described in Section 1, and Section was a fundamental study, conducted for a better understanding for desulfurization of jet fuels. More details of the results are given blow separately for the two sections