Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/28016—Particle form
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
  • B01J20/0233—Compounds of Cu, Ag, Au
  • B01J20/0237—Compounds of Cu
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
  • B01J20/0274—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04 characterised by the type of anion
  • B01J20/0285—Sulfides of compounds other than those provided for in B01J20/045
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
  • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
  • B01J20/16—Alumino-silicates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28011—Other properties, e.g. density, crush strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/2803—Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
  • C10G25/003—Specific sorbent material, not covered by C10G25/02 or C10G25/03
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/20—Characteristics of the feedstock or the products
  • C10G2300/201—Impurities
  • C10G2300/205—Metal content
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S210/00—Liquid purification or separation
  • Y10S210/902—Materials removed
  • Y10S210/911—Cumulative poison
  • Y10S210/912—Heavy metal
  • Y10S210/914—Mercury

Definitions

• This invention relates to absorbents and in particular to metal sulphide absorbents suitable for capturing mercury and/or arsenic and antimony from fluid streams.
• Mercury is found in small quantities in fluid streams such as hydrocarbon or other gas and liquid streams. Arsenic and antimony may also me found in small quantities in hydrocarbon streams. Mercury, in addition to its toxicity, can cause failure of aluminium heat exchangers and other processing equipment. Therefore there is a need to efficiently remove these metals from fluid streams, preferably as early as possible in the process flowsheet.
• Copper sulphide mercury removal materials are known.
• the pre-sulphided absorbent is prepared by forming a precursor comprising basic copper carbonate and a refractory cement binder, and then contacting the precursor with a gaseous stream containing a sulphur compound, e.g. hydrogen sulphide, so as to sulphide the copper compound.
• the pre-sulphided absorbent is then used to remove mercury from a natural gas stream.
• EP 0480603 describes a process for the removal of mercury from a stream wherein an absorbent comprising copper sulphide is prepared in situ, preferably by a mercury-containing stream also containing a sulphur compound thereby concomitantly preparing the mercury absorbent and absorbing the mercury, such that the formation of ineffective and undesired metal compounds e.g. metal sulphates, formed by oxidation of metal sulphides, is avoided.
• the Examples utilize copper and zinc sulphide materials. However, not all gas streams containing mercury also contain sulphur compounds.
• metal sulphates such as zinc sulphate, formed by the oxidation of metal sulphides other than copper sulphide
• agglomeration of the absorbent as a result of dissolution and re-deposition of metal sulphate by water present in the fluid stream.
• Re-deposition in use can cause a reduction in mercury capacity through loss in reactive copper sulphide surface area.
• Agglomeration can cause an unacceptable increase in pressure drop, and can make discharge of the absorbent from the absorption vessel difficult and lengthy. This may cause a particular problem where purification is required as part of an off-shore hydrocarbon extraction process or where purification is required in wet gas streams such as regeneration gases from dehydration units or wet carbon dioxide streams.
• the invention provides an absorbent composition suitable for removing mercury, arsenic or antimony from a fluid stream comprising 5-50% by weight of a particulate sulphided copper compound, 30-90% by weight of a particulate support material, and the remainder one or more binders, wherein the metal sulphide content of the absorbent, other than copper sulphide, is ⁇ 5% by weight.
• the invention further provides a method for making the absorbent comprising the steps of: i) forming a composition comprising a particulate copper compound capable of forming copper sulphide, a particulate support material, and one or more binders, ii) shaping the composition to form an absorbent precursor, iii) drying the absorbent precursor material, and iv) sulphiding the precursor to form the absorbent.
• the invention further provides a mercury, arsenic or antimony removal process comprising contacting a mercury-, arsenic- or antimony-containing process fluid with the absorbent.
• the absorbent comprises 5-50% by weight of a particulate sulphided copper compound.
• the sulphided copper compound therefore comprises copper sulphide.
• Preferably >90% wt of the copper is sulphided, preferably >95% wt..
• Absorbents used in the present invention preferably comprise copper in an amount 10-45% wt (expressed as the oxide, CuO), preferably, more preferably 15-30% wt Cu (as oxide) in the sulphided composition.
• the copper compound suitable for use in the absorbent is one that may be readily sulphided such as copper oxide, hydroxide and/or basic carbonate.
• One or more sulphidable copper compounds maybe used.
• a particularly suitable copper compound is basic copper carbonate (i.e. a copper hydroxycarbonate).
• the copper compound used to form the absorbent is pre-dried.
• the copper compounds are particulate and desirably are in the form of powders, preferably with an average, i.e. D 50 , particle size in the range 10-100 ⁇ m.
• the absorbents of the present invention comprise 30-90% by weight of a particulate support material.
• the support material offers a means to adapt the physical properties of the absorbent to the duty.
• the surface area, porosity and crush strength of the absorbent may suitably be tailored to its use.
• the presence of support particles can increase the strength and durability of the absorbent composition by acting as a diluent.
• the absorbent composition is then better able to retain its physical integrity during the sulphiding process, which causes a volumetric change in the copper compound as the copper sulphide is formed.
• Support materials are desirably oxide materials such as aluminas, titanias, zirconias, silicas and aluminosilicates, or mixtures of two or more of these. Hydrated oxides may also be used, for example alumina trihydrate or boehmite. Particularly suitable supports are transition aluminas, such as gamma, theta and delta alumina, and hydrated aluminas. The support may be present in an amount 30-90% wt, preferably 50-80% wt (based upon on the sulphided composition). The support materials are desirably in the form of powders with a particle size of ⁇ 100 ⁇ m, preferably 5-65 ⁇ m.
• the total metal sulphide content of the absorbent, other than other than copper sulphide is below 5% by weight. This is so that the corresponding water-soluble metal sulphates are formed in sufficiently low levels not to cause the undesirable re-deposition and agglomeration problem.
• the total metal sulphide content, other than copper sulphide is ⁇ 1 % wt, more preferably ⁇ 0.5% wt, especially ⁇ 0.1 % wt.
• the contaminant metal sulphide may be one or more of zinc sulphide, iron sulphide, nickel sulphide, chromium sulphide and manganese sulphide.
• the low contaminant metal sulphide level required by the present invention may be achieved by the selection of high purity copper compound, support and binder material, and by the exclusion of contaminant metal compounds from the composition.
• Copper compounds e.g. copper hydroxycarbonates, often contain small amounts of zinc. Hence, it is preferable that their zinc content is ⁇ 0.5% by weight (expressed as the oxide, ZnO), more preferably ⁇ 0.2% by weight (as oxide).
• the sulphided copper compound may be susceptible to the formation of copper sulphate, but we have found that this is less important that the formation and presence of the other metal sulphates, in particular zinc sulphate, which has a considerably higher solubility in water than copper sulphate under the typical conditions for mercury removal.
• the absorbent composition comprises one or more binders, making up the remaining part of the absorbent.
• the total amount of the one or more binders is in the range 2-20% by weight (based on the sulphided composition).
• the preferred binders include cement materials, including calcium aluminate cements and related materials such as ciment fondue. The cement binders react when treated with water to form stable hydrates that bind the particulate copper compound and support particles together to form a strong composition.
• the absorbent materials can undergo considerable physiochemical changes upon treatment with sulphur compounds to form the active copper sulphide phase known to be effective for mercury, arsenic or antimony removal.
• the physiochemical change even where support materials are included, can result in reduced crush strength and an increased susceptibility to attrition, particularly with high metal sulphide containing materials. It is therefore desirable to increase the crush strength whilst maintaining attrition resistance.
• a combination of binders and support material in the absorbent overcomes this problem. Furthermore, by using the two binders we have found that the amount of support material may be increased compared to prior art materials without sacrificing rate of mercury absorption, strength or attrition resistance.
• the absorbent composition comprises a first binder and a second binder, wherein the first binder is a cement binder and the second binder is a high aspect ratio binder having an aspect ratio >2.
• the first binder is preferably a cement binder, in particular a calcium aluminate cement.
• calcium aluminate cement we include such calcium aluminate compounds as calcium monoaluminate (CaO-AI 2 O 3 ), tricalcium aluminate (3CaCAI 2 O 3 ), pentacalcium trialuminate (5CaO.3AI 2 O 3 ), tricalcium penta aluminate (3CaO.5AI 2 O 3 ), dodeca calcium hepta aluminate (12CaO.7AI 2 O 3 ) and high alumina cements which may contain alumina in admixture with, dissolved in, or combined with such calcium aluminate compounds.
• a well-known commercial cement has a composition corresponding to about 18% wt calcium oxide, 79% wt alumina and 3% wt water and other oxides.
• Another suitable commercially available calcium aluminate cement has a composition corresponding to about 40% wt calcium oxide, about 37% wt alumina, about 6% wt silica and about 20% other oxides.
• the second binder is preferably a high aspect ratio binder having an aspect ratio >2.
• high aspect ratio we mean that the ratio between the maximum dimension and the minimum dimension of the particles is >2.
• the particles may thus be plate-like where the length and breadth are at least twice the thickness.
• the particles are acicular, wherein the average length is at least twice, preferably at least 2.5 times, the breadth, e.g. having a "rod” configuration wherein the cross sectional dimensions, i.e. breadth and thickness are approximately equal, or a "lath" configuration, wherein the thickness is significantly less than the breadth.
• Suitable high aspect ratio binders include clays such as aluminosilicate clays, preferably an aluminium-magnesium silicate clay, commonly referred to as an Attapulgite clay.
• aluminosilicate clays preferably an aluminium-magnesium silicate clay, commonly referred to as an Attapulgite clay.
• Attapulgite clay an aluminium-magnesium silicate clay
• the amount of the first binder may be in the range 1 to 10% by weight based on the un- sulphided absorbent precursor composition.
• the amount of the second binder may be in the range 1 to 10%, preferably 2 to 5% by weight on the un-sulphided absorbent precursor.
• the relative amounts of the binders are 1 :1 to 3:1 first to second binder.
• a particularly preferred absorbent composition comprises one or more particulate sulphided copper compounds and a particulate alumina or hydrated alumina support material, bound together with the first and second binders, wherein the zinc content of the absorbent is ⁇ 0.1 % by weight (expressed as oxide).
• the absorbent may usefully be prepared by forming a composition comprising a particulate copper compound capable of forming copper sulphide, a particulate support material, and one or more binders, shaping the composition to form an absorbent precursor, drying the absorbent precursor material, and sulphiding the absorbent precursor to form the absorbent.
• the invention also includes an absorbent precursor comprising a copper compound capable of forming copper sulphide, a particulate support material, and one or more binders, wherein the sulphidable metal content of the absorbent precursor, other than copper, is below 5% by weight (as oxide).
• the absorbent comprising the sulphided copper compound may be in any suitable physical form, e.g. as a granule, extrudate, or tablet so that the mercury-containing stream may be contacted with a bed of solid absorbent particles.
• the absorbent composition preferably has a particle size within the range 1-15 mm, more preferably 1-10 mm.
• the absorbent precursor may be in the form of tablets or pellets formed by moulding a suitable powder composition, generally containing a material such as graphite or magnesium stearate as a moulding aid, in suitably sized moulds, e.g. as in conventional tabletting or pelleting operation.
• a suitable powder composition generally containing a material such as graphite or magnesium stearate as a moulding aid, in suitably sized moulds, e.g. as in conventional tabletting or pelleting operation.
• the shaped units may be in the form of extrudes formed by forcing a suitable composition, containing the absorbent precursor material and often a little water and/or a moulding aid through a die followed by cutting the material emerging from the die into short lengths.
• extrudes may be made using a pellet mill of the type used for pelleting animal feedstuffs, wherein the mixture to be pelleted is charged to a rotating perforate cylinder through the perforations of which the mixture is forced by a bar or roller within the cylinder: the resulting extruded mixture is cut from the surface of the rotating cylinder by a doctor knife positioned to give extruded pellets of the desired length.
• the absorbent or absorbent precursor may be in the form of agglomerates formed by mixing the absorbent precursor material with a little water, insufficient to form a slurry, and then causing the composition to agglomerate into roughly spherical, but generally irregular, granules. Granulated absorbents with a particle size range of 2 to 5mm are especially preferred.
• the absorbent or absorbent precursors may be heated or treated in another way to accelerate the setting of the cement binder.
• the different shaping methods have an effect on the surface area, porosity and pore structure within the shaped articles and in turn this often has a significant effect on the absorption characteristics and on the bulk density.
• the sulphiding agent used to sulphide the absorbent precursor may be one or more sulphur compounds such as hydrogen sulphide, carbonyl sulphide, mercaptans and polysulphides, or mixtures of these. Hydrogen sulphide is preferred. Using a hydrogen sulphide-containing gas mixture is considerably easier and faster than using alternatives such as solutions of sulphur or sulphur compounds such as polysulphides.
• the gas mixture may, if desired, contain other sulphur compounds such as carbonyl sulphide or volatile mercaptans. Inert gases such as nitrogen, helium or argon may also be present.
• the sulphiding gas mixture is preferably free of reducing gases such as hydrogen and carbon monoxide, but these may be present where the sulphiding step is performed at temperatures below 15O 0 C, particularly below 100°C.
• Hydrogen sulphide is preferably provided to the precursor in gas streams at concentrations of 0.1 to 5% by volume. Sulphiding temperatures in the range 1-100°C, preferably 5-5O 0 C may be used.
• the sulphiding step may be performed on the dried absorbent precursor ex-situ in a sulphiding vessel through which a sulphiding agent is passed, or the sulphiding step may be performed in situ, in which case an absorbent precursor is installed and undergoes sulphidation in the vessel in which it is used to absorb mercury compounds.
• In-situ sulphiding may be achieved using a sulphiding agent stream or where the stream containing mercury also contains sulphur compounds, the mercury-containing stream. Where such concomitant sulphiding and mercury absorption occurs, the amount of sulphur compound that is present depends on the type of sulphur compound and metal compound used.
• the absorbent according to the present invention is preferably pre-sulphided. Pre-sulphiding avoids problems caused by the change in volume and strength of the sorbent that can accompany the sulphiding step.
• the mercury capacity of the absorbent is proportional to its sulphur content.
• very high copper sulphide absorbents often do not have the necessary strength and durability.
• copper is an expensive metal component.
• the present invention provides an optimised combination of sulphur content and physical properties compared to current commercially available materials.
• the density of the absorbent is in the range 50 to 200 kg S/m 3 .
• the present invention may be used to treat both liquid and gaseous fluids containing mercury, arsenic or antimony.
• the fluid is a hydrocarbon stream.
• the hydrocarbon stream may be a refinery hydrocarbon stream such as naphtha (e.g. containing hydrocarbons having 5 or more carbon atoms and a final atmospheric pressure boiling point of up to 204 0 C), middle distillate or atmospheric gas oil (e.g. having an atmospheric pressure boiling point range of 177 0 C to 343 0 C), vacuum gas oil (e.g.
• Refinery hydrocarbon steams also include carrier streams such as "cycle oil” as used in FCC processes and hydrocarbons used in solvent extraction.
• the hydrocarbon stream may also be a crude oil stream, particularly when the crude oil is relatively light, or a synthetic crude stream as produced from tar oil or coal extraction for example.
• Gaseous hydrocarbons may be treated using the process of the invention, e.g. natural gas or refined paraffins or olefins, for example.
• Off-shore crude oil and off-shore natural gas streams in particular may be treated with the absorbent of the present invention.
• Contaminated fuels such as petrol or diesel may also be treated.
• the hydrocarbon may be a condensate such as natural gas liquid (NGL) or liquefied petroleum gas (LPG), or gases such as a coal bed methane, landfill gas or biogas.
• Non-hydrocarbon fluids which may be treated according to the invention include carbon dioxide, which may be used in enhanced oil recovery processes or in carbon capture and storage, solvents for decaffeination of coffee, flavour and fragrance extraction, solvent extraction of coal etc.
• Fluids such as alcohols (including glycols) and ethers used in wash processes or drying processes (e.g. triethylene glycol, monoethylene glycol, RectisolTM, PurisolTM and methanol), may be treated by the inventive process.
• Mercury may also be removed from amine streams used in acid gas removal units.
• Natural oils and fats such as vegetable and fish oils may be treated by the process of the invention, optionally after further processing such as hydrogenation or transesterification e.g. to form biodiesel.
• feed streams which are susceptible to being treated by the absorbents may also include those which inherently contain both mercury, arsenic or antimony and a sulphur compound e.g. certain natural gas streams, or a mercury-, arsenic- or antimony- containing stream to which a sulphur compound has been added to effect mercury, arsenic, or antimony absorption.
• a sulphur compound e.g. certain natural gas streams, or a mercury-, arsenic- or antimony- containing stream to which a sulphur compound has been added to effect mercury, arsenic, or antimony absorption.
• the present invention is of particular utility where the fluid contains water, preferably in low levels in the range 0.02 to 1 % vol. Higher levels up to 5% vol may be tolerated for short periods.
• the absorbents of the present invention may be regenerated simply after prolonged exposure to water simply by purging with a dry gas, preferably a dry inert gas such as nitrogen.
• the absorption of mercury is conducted at a temperature below 150 0 C, preferably at or below 120 0 C in that at such temperatures the overall capacity for mercury absorption is increased. Temperatures as low as 4 0 C may be used to good effect in the present invention. A preferred temperature range is 10 to 6O 0 C.
• the mercury may be in the form of elemental mercury, or organomercuric, or organomercurous compounds.
• the present invention is particularly effective in removing elemental mercury although other forms of mercury may be removed for short periods.
• concentration of mercury in a gaseous feed stream is from 0.01 to 1100 ⁇ g/Nm 3 , and more usually between 10 to 600 ⁇ g/Nm 3 .
• Figure 1 is a graph depicting the Hg absorption profiles of a wet and a dry pre-sulphided comparative Cu/Zn/alumina absorbent not according to the invention
• absorbent precursor particles were prepared using a granulation technique wherein the solid components were combined with a little water and mixed to form granules in a Hobart mixer.
• the precursors were sulphided using a dilute hydrogen sulphide stream using known methods.
• the precursor materials were taken to a fully sulphided state using 1 % H 2 S in an inert carrier gas, (typically N 2 ) at ambient temperature and pressure.
• the lower 25 wt% by volume of the bed was made up from a pre-soaked absorbent.
• the material was immersed in demineralised water for 30 minutes at ambient temperature, then the water was decanted off and the particles touch-dried with absorbent paper.
• the remaining upper 75% by volume of the bed was dry material.
• N-hexane saturated with elemental mercury to ca. 1 ppm (w/v) was passed upwards through the bed at ambient temperature (about 2O 0 C) such that the fluid contacted the water-soaked material and then the dry material, at a Liquid Hourly Space Velocity (LHSV) of 7.0hr '1 for 750 hours.
• LHSV Liquid Hourly Space Velocity
• the dry absorbent profile is sharp, with the majority of the mercury pickup confined to the first 6-1OmI of the bed volume.
• the mercury pickup slides down the bed and results in a much lazier profile with the reaction zone being extended. This would result eventually in a faster breakthrough of mercury from the vessel.
• a second reaction front is also observed, where the mercury pickup of the bed increases at about 48% along the bed after a minimum. The minimum point at about 30% down the bed corresponds to the section of the bed that was white in colour and had agglomerated. As one progresses further down the bed, the mercury pickup increases.
• Absorbent precursor compositions were prepared in a granulator with the following compositions;
• binders comprising 10 parts of a calcium aluminate cement having a CaO content of about 40% wt, plus 4 parts Attapulgite clay).
• the granules were dried at 105 0 C in air for 16 hours after a period of 2 hours at ambient temperature (ca 2O 0 C).
• the size range of granules obtained was 1-5 mm.
• the granulated materials were sulphided in the laboratory to saturation in 1 % H 2 S to generate the active absorbent.
• An absorbent precursor composition was prepared in a granulator with the following composition
• alumina trihydrate 75 parts by weight of alumina trihydrate, 14 parts by weight of binders comprising 10 parts of a calcium aluminate cement having a CaO content of about 40% wt, plus 4 parts Attapulgite clay).
• the granules were dried at 105 0 C in air for 16 hours after a period of 2 hours at ambient temperature (ca 2O 0 C).
• the size range of granules obtained was 1-5 mm.
• the granulated materials were sulphided in the laboratory to saturation in 1 % H 2 S to generate the active absorbent.
• the sulphided absorbent was run as tested in Example 1 with the first 25% vol of the bed pre- soaked in demineralised water. The test was repeated on a commercially available presulphided 9% wt Cu (as oxide) impregnated alumina absorbent, again with the first 25% of the bed pre-soaked. The results are depicted in Figure 3.
• the absorbent according to the present invention showed no signs of agglomeration or colour change at the wet/dry interface.
• MCS mean crush strength
• the samples were outgassed at 14O 0 C for 1 hour with a nitrogen purge prior to BET surface area / isotherm measurements.

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• Analytical Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Gas Separation By Absorption (AREA)
• Treating Waste Gases (AREA)

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• 2008
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