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Method to Imrpove the Start-Up Time of Catalyst Brick in Fuel Processor

IP.com Disclosure Number: IPCOM000019949D
Publication Date: 2003-Oct-13

Publishing Venue

The IP.com Prior Art Database

Abstract

Computer modeling was used to determine catalyst brick dimensions required to give the quickest start-up of the system. The introduction of thermal disconnects to speed up the start-up time of the WGS catalyst system was also studied.

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METHOD TO IMPROVE THE START-UP TIME OF CATALYST BRICK IN FUEL

PROCESSOR

ABSTRACT

Computer modeling was used to determine catalyst brick dimensions required to give the

quickest start-up of the system. The introduction of thermal disconnects to speed up the start-up

time of the WGS catalyst system was also studied.

INTRODUCTION

Fuel cell and fuel processor designs present a number of unusual and difficult challenges

to engineers and manufacturers. Gasoline or diesel fuels are favored for many prospective

commercial applications. This is problematic, since fuel cells are far more efficient at burning

hydrogen than the hydrocarbons that comprise gasoline. Fuel processors are used to convert

hydrocarbons into hydrogen-rich fuel for a polymeric electrolyte membrane (PEM) fuel cell.

One of the major technical hurdles to PEM fuel cell commercialization is the need for a

fuel processing system that is light and small enough to fit into the confined spaces of a vehicle.

The system must also be able to perform reliably under highly variable power loads, be capable

of rapid start-up, and deliver a gas stream containing very low levels of carbon monoxide.

Carbon monoxide (CO) is a poison to all existing electro-catalysts employed in PEM fuel cells,

and its presence results in rapid degradation of performance.

The water-gas shift (WGS) reactor is a critical component of the fuel processor. Its

function is to reduce the carbon monoxide concentration to intermediate levels, which can then

be further reduced in a subsequent preferential oxidation step. However, the WGS reactor is the

single largest component in most fuel processors, accounting for one-third of the total mass,

volume, and cost. Commercial catalysts used for water-gas shift reactions are unsuitable for

transportation due to their insufficient reactivity (high weight and volume) and their tendency to

degrade under the severe conditions encountered in an automotive system. Meeting the need for

water-gas shift catalysts is critical to the commercial success of automotive PEM fuel cell

systems. Factors limiting the use of these catalysts in automobiles include the sensitivity of

today's commercial WGS catalysts to temperature fluctuations and exposure to air; size and

weight restrictions; and other operational limitations, such as the need for activation (start-up)

before use.

EXPERIMENTAL PROCEDURE

The potential advantages of reducing the start-up time of monolithic reactors in the Water

Gas Shift (WGS) catalyst systems are assessed. Using a monolithic reactor in steam reforming

of hydrocarbons has the advantages of low pressure drop, improved radial heat transfer, fast

response during transients, and high surface to volume ratio. The monolith reactor is typically

shaped as a honeycomb structure made from a ceramic or metallic substrate with numerous

straight parallel channels that have cross- sectional area or cell density varying from 600 to 1200

cells per sq in. Such a structure provides for a...