EP-4739620-A1 - STEAM REFORMING

EP4739620A1EP 4739620 A1EP4739620 A1EP 4739620A1EP-4739620-A1

Abstract

A process is described for steam reforming a hydrocarbon-containing feedstock, comprising passing a mixture of the hydrocarbon-containing feedstock and steam through a catalyst bed comprising an eggshell nickel steam reforming catalyst disposed within a plurality of tubes in a gas-heated reformer and recovering a reformed gas from the plurality of tubes, characterised in that the catalyst bed has an inlet temperature in the range of from 400 to 560 °C, an exit temperature ≤ 850 °C, and the pressure of the mixture of the hydrocarbon-containing feedstock and steam is in the range of from 30 to 100 bar abs.

Inventors

CARLSSON, MIKAEL PER UNO
Christie, Robert
DAVIES, MICHAEL
DAVIS, DAVID JONATHAN
MCKENNA, Mark Joseph

Assignees

Johnson Matthey Davy Technologies Limited

Dates

Publication Date: 20260513
Application Date: 20240604

Claims (12)

1 . A process for steam reforming a hydrocarbon-containing feedstock, comprising passing a mixture of the hydrocarbon-containing feedstock and steam through a catalyst bed comprising an eggshell nickel steam reforming catalyst disposed within a plurality of tubes in a gas-heated reformer and recovering a reformed gas from the plurality of tubes, characterised in that the catalyst bed has an inlet temperature in the range of from 400 to 560 °C, an exit temperature < 850 °C, and the pressure of the mixture of the hydrocarbon- containing feedstock and steam is in the range of from 30 to 100 bar abs.
2. A process according to claim 1 , wherein the hydrocarbon-containing feedstock comprises methane.
3. A process according to claim 1 or claim 2, wherein the mixture of hydrocarbon-containing feedstock and steam has a steam to carbon ratio in the range 1 .8:1 to 5:1 , preferably 2.0:1 to 3.5:1 , more preferably 2.0:1 to 3.2:1 .
4. A process according to any one of claims 1 to 3, wherein the temperature of the catalyst bed mid-way along the catalyst-filled tubes is in the range of from 560 to 640 °C
5. A process according to any one of claims 1 to 4, wherein the mixture of hydrocarbon- containing feedstock and steam is at a pressure in the range 35 to 100 bar abs, preferably 40 to 80 bar abs, more preferably 60 to 80 bar abs.
6. A process according to any one of claims 1 to 5, wherein the nickel is supported on a shaped particulate catalyst support.
7. A process according to claim 6, wherein the nickel is provided in a layer at the surface of the catalyst and the layer has a thickness in the range of from 250 to 700 pm, preferably 300 to 500 pm, more preferably 350 to 450 pm.
8. A process according to any one of claims 1 to 7, wherein the eggshell catalyst has a nickel content, expressed as NiO, in the range 2.5 to 9.5% by weight, preferably 2.5 to 5.5% by weight.
9. A process according to any one of claims 1 to 8, wherein the catalyst bed consists of one, two, three or more layers of nickel steam reforming catalyst wherein the layer of steam reforming catalyst adjacent outlets of the tubes is the eggshell nickel catalyst.
10. A process according to claim 9, wherein there are two or more layers of steam reforming catalyst within the tubes and the eggshell catalyst layer comprises 95% to 5% of the volume of the bed, preferably 80% to 20% of the volume of the bed, more preferably 75% to 25% of the volume of the bed.
11. A process according to any one of claims 1 to 10, wherein the reformed gas is subjected to a step of autothermal secondary reforming or partial oxidation to form a heated synthesis gas and wherein the heated synthesis gas is used to heat the plurality of tubes in the gas-heated reformer.
12. A process according to claim 11 wherein the heated synthesis gas is at a pressure less than 10 bar below, preferably less than 5 bar below, more preferably less than 2 bar below, the pressure of the mixture of the hydrocarbon-containing feedstock and steam.

Description

Steam Reforming This invention relates to a process of steam reforming hydrocarbons to produce a synthesis gas and to apparatus for carrying out the process. Synthesis gas comprises hydrogen and carbon oxides (carbon monoxide and carbon dioxide) and may contain nitrogen and other gases such as argon and low levels of methane. The synthesis gas may contain greater or lesser amounts of hydrogen and carbon oxides suited to the particular end use, such as hydrogen manufacture for refineries or fuel cells, ammonia synthesis, methanol synthesis, dimethylether synthesis or the Fischer-Tropsch process for the synthesis of liquid hydrocarbons. Synthesis gas is often produced by a steam reforming process. In a steam reforming process, a mixture of a hydrocarbon feedstock and steam, and in some cases also carbon dioxide, is passed at an elevated pressure through particulate catalyst-filled tubes, which are externally heated by a hot gas mixture, typically formed by a combusting fuel in a fired reformer. The particulate steam reforming catalyst is normally in the form of shaped units, e.g. cylinders having a plurality of through holes, and is typically formed from a refractory support material, such as alpha-alumina, calcium aluminate or magnesium aluminate, impregnated with a suitable catalytically active metal such as nickel. Eggshell catalysts, in which the active nickel component is present as a thin layer at the surface are disclosed in WO2010125369 A1 . These catalysts advantageously contain lower levels of nickel than conventional impregnated or precipitated catalysts. WO2022034283 A1 discloses the use in a steam reforming process of an eggshell steam reforming catalyst comprising 2.5 to 9.5% by weight nickel, expressed as NiO, wherein the nickel is provided in a layer at the surface of the catalyst and the thickness of layer is in the range of 100 to 1000pm. Gas-heated reformers, where the catalyst-filled tubes are heated by convection rather than radiation using a hot gas, often a synthesis gas generated by partial oxidation or secondary autothermal reforming, provide a steam reforming processes with reduced carbon dioxide emissions. However, the inlet temperatures normally used are generally too low for eggshell catalysts to perform efficiently. Furthermore, compared to fired steam reformers, the heat exchange profile in gas-heated reformers means that a greater proportion of the catalyst operates at a lower temperature, which also is disadvantageous for eggshell catalysts. We have found that certain types of eggshell catalyst may be surprisingly effective when operated at elevated pressures in gas-heated reformers. Accordingly the invention provides a process for steam reforming a hydrocarbon-containing feedstock, comprising passing a mixture of the hydrocarbon-containing feedstock and steam through a catalyst bed comprising an eggshell nickel steam reforming catalyst disposed within a plurality of tubes in a gas-heated reformer and recovering a reformed gas from the plurality of tubes, characterised in the catalyst bed has an inlet temperature in the range of from 400 to 560 °C, an exit temperature < 850 °C, and the pressure of the mixture of the hydrocarbon- containing feedstock and steam is in the range of from 30 to 100 bar abs. The use of eggshell catalyst in gas-heated reformers overcomes several problems associated with the use of conventional nickel catalysts in fired steam reformers or gas-heated reformers. The hydrocarbon-containing feedstock fed to the process may comprise any gaseous or low boiling hydrocarbon feedstock, such as natural gas, associated gas, LPG, petroleum distillate, diesel, naphtha or mixtures thereof, or off-gases from chemical processes, such as a refinery off-gas, or a pre-reformed gas. The hydrocarbon-containing feedstock preferably comprises methane and may be a pre-reformed gas, an associated gas or natural gas. Natural gas is an especially preferred feedstock. The feedstock may be compressed to a pressure in the range 30 to 100 bar abs. The pressure of the hydrocarbon-containing feedstock may usefully govern the pressure throughout the process. The pressure of the mixture of the hydrocarbon- containing feedstock and steam is in the range of 30 to 100 bar abs. The pressure of the mixture of the hydrocarbon-containing feedstock and steam is preferably in the range of 35 to 100 bar abs, more preferably 40 to 80 bar abs, most preferably 60 to 80 bar abs as this provides an enhanced performance from the process. If the hydrocarbon-containing feedstock contains sulphur compounds before or, preferably, after compression, the feedstock may be subjected to desulphurisation. Desulphurisation may comprise hydrodesulphurisation using CoMo or NiMo catalysts, and absorption of hydrogen sulphide using a suitable hydrogen sulphide absorbent, e.g. a zinc oxide adsorbent. An ultrapurification adsorbent may usefully be used downstream of the hydrogen sulphide adsorbent to further protect