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Hydrogen production process

a hydrogen production process and hydrogen technology, applied in the direction of hydrogen/synthetic gas production, chemistry apparatus and processes, inorganic chemistry, etc., can solve the problems of high steam to carbon ratio disadvantageously increasing energy consumption in the hydrogen production process, rapid sintering and reduction of activity, etc., to reduce steam requirements

Inactive Publication Date: 2008-10-23
LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0011]It is a further object of the present invention to reduce steam requirements below five moles of steam for every carbon atom bound in a hydrocarbon or oxygenated hydrocarbon molecule in the feedstock, particularly for those feedstocks having average carbon numbers of 2 or more.

Problems solved by technology

If hydrocarbon or alcohol feedstocks enriched in compounds with two or more carbon atoms per molecule (C2+ hydrocarbons) are used for hydrogen generation, the risk of catalyst deactivation by carbon deposition is greatly increased.
High steam to carbon ratios disadvantageously increase energy usage in the hydrogen production process.
First, they are subject to rapid sintering and reduction of activity if feedstock temperature is not controlled very closely.
Second, they present substantial safety risk due to their pyrophoric reaction with oxygen, especially when nickel metal is used, thus necessitating great care in handling the catalysts during reduction and subsequent operation.
Further, even at the elevated steam to carbon ratios employed in existing hydrogen production processes using pre-reformers for C2+ feedstocks, deactivation by carbon deposition remains a problem.
These promoters are very effective, but disadvantageously reduce catalyst reaction rate, necessitating larger pre-reforming reactors.
Further, the promoters tend to volatilize and subsequently deposit on downstream catalysts and equipment.
This causes deactivation of downstream catalysts and potential corrosion damage to equipment, both of which may lead to serious operation problems such as hot banding of reformer tubes, carbon deposition and eventual tube failure.
Further, the protective effects of the alkali promoters are lost after they are volatilized, such that eventual catalyst failure is assured in existing pre-reformers.

Method used

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Examples

Experimental program
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Effect test

example 1

[0035]Propane was used as hydrocarbon feedstock having three carbon atoms. A reactor vessel having 1.4″ ID was loaded with 10 g of catalyst having 1 wt % Ir deposited on a non-reducible oxide support comprising barium hexaaluminate, making an approximately 1 cm deep catalyst bed. The pre-reforming reaction was conducted under nearly adiabatic conditions. Two ˜2 cm deep layers of 3 mm glass beads were placed below and above the catalyst bed to provide uniform flow of reacting gas through the bed. Two thermocouples were installed just below and above the catalyst bed to measure the temperature differential across the catalyst.

[0036]The reactor was placed in a furnace and the furnace temperature was set constant at 450° C. Propane and steam flows were constant at a molar steam to carbon ratio, or S:C=3.7. Hydrogen flow was changed stepwise between hydrogen stoichiometry λ of 1.5, 1, 0.5, 0.25 and 0.13. Overall gas space velocity was approximately 35,000 l / hr. The reactor was stabilized...

example 2

[0039]The catalyst of Example 1 was aged for about 1500 hrs in the steam methane reforming (SMR) reaction. The catalyst was then removed and loaded into the reactor of Example 1. The same testing procedure was used as described above. Table 2 shows the results for the second catalyst testing.

TABLE 2HydrogenC3H8stoichiometry, λconversionΔT1.530−21123−140.513−10.255100.13112After aging overnight1.519−11116−50.5930.25490.13110

[0040]For an aged catalyst, the method of the present invention yields a surprising increase in C2+ hydrocarbon conversion with increasing hydrogen stoichiometry, λ. Furthermore, the exothermic temperature change increases with increased hydrogen stoichiometry within the inventive range.

example 3

[0041]Ten grams of fresh FCR-69-4 catalyst obtained from Sud-Chemie Corporation was loaded into the same test vessel. The same testing procedure was used as described above, with results shown in Table 3. This catalyst has a metal loading of approximately 4 wt % Iridum on an alumina carrier promoted with a mixture of rare earth oxides, namely, CeO2 at 14-20 wt %, La2O3 at 1-5 wt %, and Y2O3 at 1-5 wt %, based on amount of catalyst.

TABLE 3HydrogenationstoichiometryC3H8of feed, λconversionΔT1.594N / A192N / A0.587N / A0.2581N / A0.1376N / AAfter aging overnight1.588N / A186N / A0.580N / A0.2573N / A0.1367N / A

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Abstract

A hydrogen production process includes combining a first feedstream and a second feedstream to produce, in a pre-reforming reactor, a first product stream comprising CH4 and H2O; wherein the first feedstream contains a mixture of H2 and at least one selected from the group consisting of hydrocarbons having two or more carbon atoms and alcohols having two or more carbon atoms, and the mixture has a hydrogen stoichiometric ratio (λ) of at least 0.1, and the second feedstream contains steam;feeding the first product stream into a reforming reactor; andreacting the first product stream in the reforming reactor to produce a second product stream containing CO and H2;and a catalyst for use in the process.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to processes for producing hydrogen. In particular, the present invention relates to processes for producing hydrogen through steam reforming.[0003]2. Discussion of the Background[0004]Hydrogen production is typically performed through catalytic steam reforming. The general reaction for catalytic steam reforming is as follows:CxHyOz+(x-z)H2O→catalystxCO+(x-z+yz)H2[0005]Steam reforming is an endothermic reaction carried out either in heat exchange reactors, or by other means where substantial heat may be transferred to the reacting fluid, such as in the case of autothermal reforming, where a portion of the feedstock is combusted inside the reactor to provide heat for steam reforming either subsequently or in the same location as the combustion. If hydrocarbon or alcohol feedstocks enriched in compounds with two or more carbon atoms per molecule (C2+ hydrocarbons) are used for hydrogen genera...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C01B3/26C01B3/24
CPCC01B3/382C01B2203/0233C01B2203/1005C01B2203/1017C01B2203/1023C01B2203/1047C01B2203/1082C01B2203/1094C01B2203/1247C01B2203/127C01B2203/142
Inventor LOMAX, FRANKLIN D.LYUBOVSKY, MAXIMZAKARIA, RAMAWAGNER, JON P.RATNASAMY, CHANDRA
Owner LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE