Hydrogenolysis Operations Manual

565 views
474 views

Published on

Introduction
VULCAN Series VHT-S101
Catalyst storage, handling, charging
Health and safety precautions
Start-up of VHT-S101 hydrogenation catalyst
Operation of VHT-S101 hydrogenation catalyst
Shut-down of VHT-S101 hydrogenation catalyst
Sulfiding of hydrodesulfurization catalysts
Catalyst Discharge

Published in: Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
565
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
60
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Hydrogenolysis Operations Manual

  1. 1. 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 GBH Enterprises, Ltd. Operating Manual Hydrogenation Catalysts VHT-S101 hydrogenation catalyst
  2. 2. 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 Contents Introduction VULCAN Series VHT-S101 Catalyst storage, handling, charging Health and safety precautions Start-up of VHT-S101 hydrogenation catalyst Operation of VHT-S101 hydrogenation catalyst Shut-down of VHT-S101 hydrogenation catalyst Sulfiding of hydrodesulfurization catalysts Catalyst Discharge Information contained in this publication or as otherwise supplied to Users is believed to be accurate and correct at time of going to press, and is given in good faith, but it is for the User to satisfy itself of the suitability of the product for its own particular purpose. GBH Enterprises, Ltd., Catalyst Process Technology gives no warranty as to the fitness of the Product for any particular purpose and any implied warranty or condition (statutory or otherwise) is excluded except to the extent that exclusion is prevented by law. GBH Enterprises, Ltd., Catalyst Process Technology accepts no liability for loss or damage, resulting from reliance on this information.
  3. 3. 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 INTRODUCTION Sulfur and chlorine compounds are particularly severe poisons for nickel, iron and copper catalysts used in plants utilizing steam reforming technology for the production of hydrogen and hydrogen/carbon monoxide mixtures for downstream use in oil refining, petrochemical, ammonia and methanol production. The large volumes of hydrocarbon feedstock to be processed mean that even small traces of these poisons have a cumulative detrimental effect on the performance of downstream catalysts. It is therefore extremely important to purify all the hydrocarbon feedstocks before they are processed to achieve the long production runs needed for economic operation. Organic sulfur compounds must be hydrogenolysed over VHT-S101 or VHT- S103 to convert the sulfur to hydrogen sulfide (H2S). Where present, organic chloride compounds are also hydrogenolysed over VHT-S101 or VHT-S103 to give hydrogen chloride (HCI), which is then removed by absorption with VSG- CL101. Lastly, the H2S is removed by absorption with VSG-S201 or VSG- EZ200. This manual discusses the principles of start-up, operation and shut down and the information provided is sufficient for the preparation of detailed operating instructions, which of necessity will be plant specific.
  4. 4. 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 VULCAN Series VHT-S101 Hydrodesulfurization catalysts GBH Enterprises, Ltd., Catalyst Process Technology supplies two catalysts for hydrodesulphurization (HDS), namely VHT-S101 and VHT-S103 which are respectively based on cobalt oxide/molybdenum oxide and nickel oxide/molybdenum oxide, in both cases supported on alumina. VHT-S101 is more commonly used for ammonia and hydrogen duties while VHT-S103 is usually used in methanol plants. The catalysts achieve their highest activity when sulfided but can also operate under low sulfur conditions when partially sulfided. In most applications, the catalysts do not need a special sulfiding stage and an appropriate level of sulfiding is attained by reaction with the sulfur compounds in the hydrocarbon feed. VHT-S101 and VHT-S103 normally operate at temperatures in the range of 300- 400ºC (570-750ºF) and at pressures of 25-40 bar (363-580 psi). The preferred operating temperature is towards the upper end of this range. In certain circumstances, it is advisable to pre-sulfide the HDS catalyst. These circumstances are limited to situations where the carbon oxides concentration is high presenting a risk of exothermic methanation; the sulfur concentration is very low such that inadequate sulfiding will occur; the operating temperature is low such that maximum HDS activity is necessitated from start of run; the organic sulfur level is high again necessitating maximum activity immediately on commissioning; and the nature of the hydrocarbon feed and partial pressure of hydrogen present a risk that an exothermic hydrocracking reaction may initiate. Pre-sulfiding of the catalyst is achieved either by an in situ sulfide pre-treatment or by supply of pre-sulfided catalyst. In these situations, GBH Enterprises, Ltd., Catalyst Process Technology will advise on the appropriate catalyst selection and procedures. Composition VHT-S101 Cobalt oxide/ Molybdenum Oxide/Alumina Physical and Chemical Properties Appearance Blue Gray Extrude Cylinder Size, mm Φ3.0 Components Co, Mo, γ-Al2O3 Bulk Density, kg/l 0.65-0.75 (typically 0.72) Crushing Strength, N/cm ≥80 Attrition loss, % ≤3.0
  5. 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 Catalyst storage, handling, charging and discharging Before charging, discharging and handling shift catalysts any potential risk to health during these activities should be assessed and appropriate precautions taken. In addition the GBH Enterprises Catalysts brochure on “Catalyst Handling” should be consulted. Drum storage Shift catalysts are generally supplied in mild steel drums, fitted with polythene liners, and having the following packaging details. Precise information will be recorded in the documentation covering the goods when supplied. Drums must not be stacked on their sides or stacked more than four drums high, even when held on pallets. Taller stacks tend to be unstable and there is the risk that the top drums may fall off the stack, and the lower drums can be crushed due to the weight of the drums above them. The metal drums are usually suitable for outside storage for a few months but should be protected against rain and standing water. If prolonged storage is expected, they should be kept under cover and away from damp walls and floors. The lids should be left on the drums until just before the catalyst is to be charged. If the lids are removed it is important that they should be replaced as soon as possible, so that contamination of the catalyst is avoided. If the drum lid cannot be replaced, then the catalyst should be redrummed without delay. If any contamination occurs it is difficult to assess the extent of any damage without full examination of the catalyst. If there is any doubt about the state of the catalyst it is best not to charge it to the reactor. Drum handling Catalyst drums should be handled as carefully as possible. They must not be rolled. Catalyst drums are often supplied on pallets, which reduces the likelihood of damage in transit but requires suitable fork-lift trucks and a paved area to handle the pallets. The fork-lift truck to be used for dismantling the pallets should be fitted with rim or body clamps to avoid damage to the drums. The use of shipping containers for either catalyst drums or palleted drums eases shipment and further reduces the likelihood of damage in transit. It is important not to use standard forks to lift the drums under the rolling hoops, as damage to the drums and catalyst is almost inevitable.
  6. 6. 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 Sieving catalyst Catalysts are screened before they are packed into drums for dispatch, hence sieving on site is not usually required, but in some instances attrition can occur in transit if the drums are roughly handled. In this case some form of screening is advisable before charging, especially if the catalyst appears to contain dust on delivery. A good method of sieving is to pass the catalyst over a simple inclined screen. This is often the most satisfactory method, since vibrating screens can cause additional unnecessary damage and loss. The screen should contain provision to collect the dust, and at the same time avoid generating a dusty atmosphere. The mesh spacing should be about half the smallest dimension of the catalyst pellet. While the catalyst is being poured over the screen, the use of a vacuum system situated close to the sieve will control the dust effectively. Pre-charging checks Before the catalyst is charged it is important that the condition of the catalyst support grid in the vessel and any supporting materials such as inert balls be checked. Some form of light metal shield or “spider” fitted into the discharge manhole prevents inadvertent catalyst discharge when the manhole cover is removed. The vessel should be clean, dry and free from loose scale and debris. It is important to ensure that the charging level is clearly defined, so as to avoid under filling or overfilling. The desired level can be marked with chalk before charging is commenced. It can be valuable to check that thermocouples are correctly installed before charging is commenced by warming them in turn to ensure that the correct indication is given on the instrument panel.
  7. 7. 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 Charging the Hydrogenation Vessel The catalyst may be loaded directly from the drums or from intermediate bulk containers. The general rules for charging catalysts into vessels are: • The catalysts should have a free fall of between 50 and 100 cm (20-40 inches) to ensure a suitable packed density is achieved. (More than 100 cm/40 inches may damage the catalyst) • The catalyst must be distributed evenly as the bed is filled, with a maximum height difference of 15 cm (6 inches) across the bed when completed. Health and safety precautions Operators should be aware of the hazards associated with the use of catalyst and draw up the appropriate safety instructions. Discharge of pyrophoric catalyst Catalysts discharged in the pyrophoric state must be kept separate from flammable materials. Transport of such catalyst should only be in metal skips or metal sided trucks. Dumps of the catalyst should be within reach of water hoses so that any overheating that occurs can be controlled. High temperatures can build up in heaps and it is a prudent precaution to spread the catalyst thinly over the ground until the oxidations is complete. Under no circumstances should personnel be allowed to walk over the catalyst until it has been fully stabilized. The normal shut-down procedure for inert discharge is as follows Dust exposure Short term exposure to the metals and metal oxides used in catalysts may give rise to irritation of the skin, eyes and respiratory system. Over-exposure can give rise to more serious effects. Product safety data sheets should be consulted for information. Catalysts should be handled as far as possible in well-ventilated areas and in a way which avoids the excessive formation of dust. Operators who handle catalyst must wear suitable protective body clothing, gloves and goggles. Inhalation of dust should be avoided, and the appropriate occupational exposure limits should be strictly observed. If these limits are likely to be exceeded, then respiratory protections should be used. Everyone involved in the handling operation should clean up afterwards and, in particular, must wash before eating.
  8. 8. 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 Clothing should be changed at the end of each shift, and more frequently if contamination is heavy. Ergonomics Physical hazards arise from the handling of drums, materials and lifting equipment. Personnel should be aware of these and appropriate precautions taken. Note: The European Union has decided that it is prudent to classify all insoluble nickel compounds as Category 1 carcinogens. Appropriate information is contained in the Material Safety Data Sheet sent with all orders. Start-up of VULCAN Series VHT-S101 When using VHT-S101 for the hydrodesulphurization of light hydrocarbons and gaseous feedstocks no special activation procedures are usually necessary. Conversion to the more active sulfided form is achieved to a sufficient extent by reaction with sulfur compounds in the feed gas. 1 Purge the vessel free of oxygen using an inert gas or natural gas. The latter is used of necessity where there is no available nitrogen system, for example in certain ammonia plant designs. 2 Heat the catalyst in a flow of inert gas or natural gas at a rate not exceeding 50ºC (90ºF) per hour. The alumina support will usually contain adsorbed moisture which will be evolved during the heating stage. The HDS catalyst and downstream absorbents should be heated to at least 300°C (572°F) (and ideally to design operating temperature) before the system is commissioned for hydrodesulfurization with feed forward to the steam reforming section. 3 If the catalyst is heated up with natural gas, care is needed with regard to any sulfur compounds. Organic sulfur impurities will not be absorbed by the H2S removal absorbent downstream and may not react effectively over the HDS catalyst until the hydrogen flow has been introduced and the catalyst temperature exceeds 300°C (572°F). Care is required, therefore, that impure natural gas does not pass to the steam reformer during the heating phase and conditions are such that sulfur impurities are being removed before feeding gas forward.
  9. 9. 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 Raising the pressure will aid heat transfer. The HDS catalyst vessel may be brought up to operating pressure at any time during the heating stage, however, a lower pressure may be preferred at this stage depending on the status of the reduction of the downstream steam reforming catalyst. If this is the case, pressure should be raised later in line with the requirements of the steam reformer commissioning. 5 The feed gas and hydrogen, or hydrogen rich gas, may be introduced with the temperature below 300°C (572°F) in order to begin sulfiding of the catalyst with the more reactive sulfur compounds in the feed as long as it is possible to route this gas elsewhere than the steam reforming section. Important: If hydrogen rich gas contains carbon oxides then these could methanate over the unsulfided catalyst at temperatures above 300ºC (570ºF). The gas temperature will increase by about 50ºC (90ºF) for every 1% of carbon oxides which reacts. If the catalyst temperature can then exceed the design value it will be necessary to introduce the hydrocarbon feedstock before the hydrogen rich gas at an inlet temperature below 300ºC (570ºF) in order to dilute the carbon oxides to an acceptable level. Hydrocarbon that is not completely desulfurized during this stage should not pass to the primary reformer. When VHT-S101 is used to desulfurize steam reformer feedstocks, commissioning often proceeds with the start-up of the reforming furnace. The desulphurization vessel may be included in the reformer recycle loop and hydrocarbon feedstock can only be added at the appropriate stage in the reforming catalyst reduction. This may mean that the unsulfided catalyst is in contact with hydrogen at the normal operating temperature before sulfur containing gas can be admitted. Prolonged exposure to hydrogen alone should be avoided as this can lead to over reduction of the catalyst but experience indicates that subsequent problems are very rare. Several variations of the recommended start-up procedure are possible in particular plants. For example, if VHT-S101 is being used to hydrodesulfurize gas streams the gas feedstock can be used to heat the vessel in stage 2 of the start up procedure. It is also possible to desulfurize gas at low throughput rates for steam reforming plants as soon as the catalyst bed temperature exceeds 300ºC (570ºF), but is still less than the design temperature, if this is an advantage. It is always important, however, on these occasions to monitor the sulfur content of gas leaving the zinc oxide. This is to confirm that adequate purification has been achieved before passing it to the reformer.
  10. 10. 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 Operation of VULCAN Series VHT-S101 VHT-S101 is robust and gives trouble-free operation for many years. Performance is usually checked by measuring the feedstock sulfur content and the sulfur content of gas leaving the final bed of zinc oxide. Any instantaneous changes in sulfur slip will often be noticed first from the performance of the reformer. It is possible to check on the extent of hydrogenolysis of organic sulfur compounds across the bed of cobalt catalyst but this requires sophisticated analytical equipment. VHT-S101 evolves or absorbs sulfur as the sulfur content of process gas changes. This corresponds to changes in the sulfide content of the catalysts due to equilibration with the changing process gas sulfur level. Any evolved sulfur will be in the form of H2S which is removed in the downstream absorbent beds. There will normally be no detectable temperature rise across the catalyst bed unless olefins are present which will then be hydrogenated. Depending on the temperature rise observed it may be necessary to decrease the inlet temperature to the vessel to maintain the exit temperature at the design maximum. When operating with VHT-S101 it should be remembered that: 1 Performance is closely related to the quantity of sulfur and the particular sulfur compounds present in the feed gas. 2 Hydrodesulphurization is not possible in the absence of hydrogen. 3 Activity is strongly temperature dependent so that operation below design conditions is not recommended. 4 Operation above 400ºC (750ºF) should be avoided to achieve best results and to prevent hydrocracking. 5 Olefins present will hydrogenate and consume hydrogen. Not only will this produce an exotherm but also it may not leave enough hydrogen for the hydrogenolysis of organic sulfur compounds.
  11. 11. 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 6 This catalyst is an effective shift catalyst therefore if CO2 is present in the feed an allowance should be made for the hydrogen consumed in the reverse water gas shift reaction. CO2 + H2 CO + H2O Shut-down of VHT-S101 During a plant shut-down, hydrodesulphurization catalyst may normally be left in an atmosphere of the process gas without any damage to the catalyst. Where there is a likelihood of some condensation of the hydrocarbon feedstock, for example in a naphtha based plant, the reactor should be purged with an inert gas. Similarly if carbon oxides are present the reactor should be purged with an inert gas to avoid the risk of methanation occurring. Hydrodesulphurization catalysts in the sulfided from are potentially pyrophoric, due to finely-divided carbon that can be present. This and any adsorbed hydrogen or feedstock can ignite when the catalyst is discharged hot from the vessel. For this reason if the catalyst is to be discharged the procedure outlined under “Catalyst Discharge” must be used. Under no circumstances should air be passed through the catalyst until it has been cooled to below 50ºC (90ºF). Sulfiding of hydrodesulphurization catalysts HDS catalysts can be sulfided if required by doping with a sulfur compound to ensure maximum activity during initial operation and also to inhibit methanation of carbon oxides in feed gas or hydrogen recycle. During normal operation the HDS catalyst will reach an equilibrium sulfur content which depends on the level of sulfur in the feedstock. If more sulfur than this is added during sulfiding the excess will be displaced when operation begins and shorten the life of the zinc oxide bed. It is recommended, therefore, that only about 2% w/w sulfur be added during the procedure.
  12. 12. 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 1 Purge the reactor free of oxygen using an inert gas. 2 Heat the catalyst to 200ºC (392ºF) in a flow of inert gas or natural gas at a rate not exceeding 50ºC (90ºF) per hour. Pressure may be in the range of 10-20 bar (150-300 psi). Introduce about 5-10% hydrogen and add about 1% of carbon disulfide, dimethyl disulfide, mercaptan or hydrogen sulfide. The space velocity should be about 400-600 hr-1 and sulfiding should continue until the catalyst has picked up 1-2% w/w sulfur. 3 Discontinue sulfur addition. 4 If feedstock plus hydrogen has been used as the carrier the catalyst bed temperature should be increased at a rate not exceeding 50ºC (90ºF) per hour to the operating temperature. It is ready for use. If an inert gas plus hydrogen has been used as the carrier during sulfiding it should be replaced with feedstock plus hydrogen before increasing the temperature to the operating level. The importance of sulfiding HDS catalysts when high concentrations (greater than 10% v/v) of carbon oxides are present in either recycle hydrogen, or feedstock, must always be remembered. It is also very important to monitor the sulfur content of gas leaving the zinc oxide catalyst during the commissioning period to check that adequate purification has been achieved when presulfided HDS catalysts are being used and excess sulfur is being evolved. Catalyst discharge and disposal The catalyst or absorbent is usually discharged from the reactor with large mobile vacuum units or by gravity flow from the bottom of the vessel. The spent material should be assumed to be potentially combustible because of adsorbed hydrogen and hydrocarbons or finely-divided carbon that can be present. When discharging from the vessel the following procedure should be used. 1 Purge the reactor free of hydrocarbon using an inert gas and reduce the pressure. 2 Cool the reactor to below 50ºC (90ºF) in a flow of inert gas.
  13. 13. 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 Discharge the catalyst or absorbent under a positive pressure of inert gas. This may be by vacuum extraction or by gravity flow from the bottom of the converter. In the latter case, as the material falls from the bottom manhole, water hoses should be available to wet it in case it overheats. If the material has to be discharged when it is hot it should be assumed that it is pyrophoric and the following procedure used. 1 Purge the desulfurizer vessel with an inert gas and reduce the pressure. Maintain a positive pressure of the inert gas in the vessel. 2 Discharge the catalyst or absorbent into metal bins or metal-sided lorries with only the discharge manhole open. Air must NOT be allowed to enter the vessel otherwise local overheating could take place. 3 Water hoses should be available in case of overheating. Water should not be used unless necessary as this could cause breakdown of the catalyst or absorbent particles. GBH Enterprises, Ltd., Catalyst Process Technology offers advice on the environmentally safe disposal of its complete product range.

×