Procedure for Naphtha Steam Reforming Catalyst Reduction with Methanol
Scope
This procedure applies to the in situ reduction of VULCAN Series steam reforming catalysts using methanol cracking to form hydrogen over the catalyst in the steam reformer.
The procedure is likely to be applied to plants using only heavier feeds (e.g.: LPG and/or naphtha) and some combination of VULCAN Series catalysts.
Introduction
A small number of steam reforming plants do not have an available source of the commonly used reducing media (e.g.: hydrogen, hydrogen-rich off-gas, natural gas). These plants will usually operate on LPG and/or naphtha feed only where cracking of this hydrocarbon is not usually advised for reduction of the steam reforming catalyst ...
Naphtha Steam Reforming Catalyst Reduction with Methanol
1. GBH Enterprises, Ltd.
Naphtha Steam Reforming Catalyst
Reduction with Methanol
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Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
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2. Naphtha Steam Reforming Catalyst Reduction with Methanol
Scope
This procedure applies to the in situ reduction of VULCAN Series steam
reforming catalysts using methanol cracking to form hydrogen over the catalyst in
the steam reformer.
The procedure is likely to be applied to plants using only heavier feeds (e.g.: LPG
and/or naphtha) and some combination of VULCAN Series catalysts.
Introduction
A small number of steam reforming plants do not have an available source of the
commonly used reducing media (e.g.: hydrogen, hydrogen-rich off-gas, natural
gas). These plants will usually operate on LPG and/or naphtha feed only where
cracking of this hydrocarbon is not usually advised for reduction of the steam
reforming catalyst. In such circumstances, the plant may be designed to use the
installed steam reforming catalyst to crack methanol to provide hydrogen for the
reformer catalyst reduction. A once through method should be used to avoid
the potential of methanation of carbon oxides produced in the methanol
cracking. By control of the steam to methanol ratio and reformer exit
temperature, oxidized catalyst cracks methanol to generate hydrogen which then
effects a degree of catalyst reduction. Once some reduced nickel is present,
methanol cracking becomes efficient and the period in which methanol is
observed in the process condensate is kept to a minimum.
Procedure
1. Ensure the primary reformer catalyst is heated in a nitrogen flow to above the
dew point of the process stream. Once this temperature is exceeded by at
least 50°C (90°F), continue heating with process steam. The system pressure
should be in the usual range for the reformer start-up circulation loop
(typically 10 – 15 bara).
Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
3. 2. Heat the reformer to a measured inlet temperature in the range 475 to 500°C
(887-932°F) and a measured exit temperature of 780 to 800°C (14361472°F). If the plant design does not allow the inlet temperature to attain this
level, then the inlet temperature should be as high as possible within the
constraints of the plant. Temperature losses to the point of exit temperature
measurement are usual at this low load of operation and the actual tube exit
temperature will be higher than these values. Regular (1/2 hourly)
inspections, ideally with an accurate IR pyrometer, of the reformer are
necessary to check for possible overheating.
3. At the above temperatures, control the steam flow through the primary
reformer insofar as this is possible to remain within tube skin temperature
limits and to satisfy the ratio of steam to methanol as specified in (4)
4. Inject methanol at an initial rate to satisfy a steam to methanol molar ratio of
an absolute minimum of 25:1. This will be sufficient to carry-out the catalyst
reduction, but the process will be slow and methanol will be present in the
condensate for the period. To minimize the time to produce hydrogen and
limit the amount of methanol in the condensate, lower molar ratios of steam to
methanol should be targeted in the range 20:1 to 18:1.
5. Process condensate containing methanol will need proper attention. Initial
levels of methanol could exceed 1000 ppmw, but will reduce quickly once
cracking occurs over the reforming catalyst
6. Maintain continuous methanol injection at the required rate for at least one (1)
hour.
7. Take samples for analysis of the reformer exit for hydrogen and process
condensate for methanol every 30 minutes over the first two hours of
methanol injection. Thereafter, reduce the frequency to every 60 minutes for
as long as necessary.
8. If no hydrogen is detected after 2 hours and the methanol levels in the
process condensate remain high (>>100 ppmw), then the molar ratio of
methanol to steam is possibly incorrect and/or the reforming temperature is
low.
Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
4. 9. Once hydrogen is measured, the H2O/H2 molar ratio should be recorded (from
a combination of analysis and calculation of the amount injected and cracked
methanol). The target point is when the H2O/H2 molar ratio enters the target
reduction range of 6:1 – 8:1. The molar ratio may be allowed to go as low as
4:1 without cause for concern in terms of the catalysts.
10. Once the H2O/H2 molar ratio is in the range 6:1 – 8:1, maintain the methanol
injection rate. Continue to analyze at 60-minute intervals and calculate the
H2O/H2 molar ratio in the exit.
11. Maintain reducing conditions (H2O/H2 molar ratio in the range 6:1 – 8:1) for
the following times depending on the recent shutdown history of the catalyst.
See Table 1.
12. Following this, introduce hydrocarbon feed as described in the Operating
Manual for VULCAN Series Naphtha Steam Reforming Catalysts.
Table 1 – Catalyst Reduction Times
Catalyst Steaming
Period
(Hours)
<3
3-8
>8
Fresh Catalyst Charge
Period of Reduction
(Hours)
No reduction required
6 hours of reduction
12 hours of reduction
18 hours of reduction
Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com
5. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown
Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass
Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance
Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts /
Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals
Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries
Web Site: www.GBHEnterprises.com