| Identification | More | [Name]
Palladium | [CAS]
7440-05-3 | [Synonyms]
1%PD
ATen
10%Pd
Pd-C1FI
AlladiuM
PD007940
PD004700
PD005146
PD000260
PD005116
PD000202
PD007200
PD007260
PD000203
PD000240
PD000255
PD000205
PD005120
PD000276
PD000262
PD000278
PD000275
PD000200
PD000263
PD000270
PD005155
PD005100
PD005113
PD000290
PD000272
PD000310
PD005110
PD000250
PD000261
PD007100
PD005140
PD000350
PD005130
PD004500
PD000190
PD000300
PD000241
PD005150
PD007150
PD007250
PD000206
Paladium
PD004600
PD000256
PD000201
PD007920
PD000251
PD000351
PD007950
PD000204
PD000180
PD004300
PD000170
PD000264
PALLADIUM
PALLIDIUM
ESCAT 1351
ESCAT 1371
ESCAT 1391
Palladium1
Palladium2
Palladium3
Palladium4
Palladium6
palladex600
Pd/CaCO3 5%
Palladium、Pd
palladium 10%
ESCAT TM 1351
ESCAT TM 1371
ESCAT TM 1391
Palladium rod
Palladium, 1%
Palladium, 5%
Palladium shot
Palladium foil
Palladium (3%)
PD(OH)2 CARBON
Palladium wire
PalladiumaufAlO
adium on carbon
SIMMONS CITRATE
PALLADIUM ALLOY
AlladiuM soluion
palladium，foamed
palladiumelement
Palladium (0.5%)
PalladiumaufBaSO
PalladiumaufCaCO
LINDLAR CATALYST
PALLADIUM 99.999%
Alladium Standard
PALLADIUM CARBONE
PALLADIUM ASBESTOS
Palladium powdered
Rosenmund catalyst
Palladium, 5 wt. %
Palladium granules
Palladiumpowdermesh
PALLADIUM ON SILICA
Palladium on calcium
PalladiumpowderNmesh
Palladiumshot(99.9%)
Palladium Carbon 10%
Palladium/C catalyst
Palladium nanosheets
Palladium 5% on BaSO4
Palladium high purity
Pd/C Palladium/Carbon
Palladium Wire 2.0 mm
PALLADIUM ON GRAPHITE
Paladium(Metal)Powder
Palladiumblack(99.9%)
Palladiumfoil(99.95%)
Palladiumrod(99.95+%)
PD/CU PALLADIUM ALLOY
Palladium foil25x25mm
Palladium foil50x50mm
PALLADIUM TARGET 99.9%
PALLADIUM 5% ON SILICA
PALLADIUM 1% ON SILICA
onactivatedcarbon10%Pd
PALLADIUM, 5% ON AL2O3
PALLADIUM BLACK: 98.5%
5% PALLADIUM ON CARBON
Palladium carbon black
Palladium wire (99.9%)
Palladium 5% auf Al2O3
Palladium 5% auf BaSO4
Palladium 5% auf CaCO3
Palladium 99+ powdered
precipitated palladium
PALLADIUM, 5% ON CACO3
PALLADIUM ON CARBON 5%
Palladium nanoparticles
PalladiumrodNmmdiacagmm
PALLADIUM, 99.9+%, FOIL
Palladium, foil, 99.9+%
PALLADIUM POWDER: 99.5%
Palladium black, 98% Pd
Palladium, 5% on carbon
PALLADIUM POWDER 99.99%
PALLADIUM 1% ON ALUMINA
PALLADIUM SPONGE 99.99%
PALLADIUM TARGET 99.95%
PALLADIUM 0.5% ON RESIN
PALLADIUM TARGET 99.99%
PALLADIUM 10% ON CARBON
PALLADIUM 5% ON ALUMINA
Palladium foil100x100mm
PALLADIUM TARGET 99.999%
PALLADIUM SPONGE 99.995%
PALLADIUM 5% ON GRAPHITE
PALLADIUM 0.5% ON CARBON
PALLADIUM POWDER 99.999%
PDAG/ZBN PALLADIUM ALLOY
PALLADIUM SPONGE 99.999%
1.0MM DIA. (~0.94G/10CM)
PALLADIUM, 10% ON SILICA
PalladiumwireNmmdiacagmm
Palladium sponge (99.9%)
PALLADIUM CACO3 CATALYST
Palladium on alumina（5%）
Palladium on alumina（1%）
palladiuM on carbon(10%)
Palladium (8CI, 9CI, ACI)
Palladium rod, dia 6.35mm
LINDLAR CATALYST, REDUCED
Palladium sponge (99.95%)
PalladiumspongeNgraysolid
PALLADIUM SHOT, 3N: 99.9%
Palladium, 99.99%, powder
Palladium, sponge, 99.90%
PALLADIUM, 99.90%, SPONGE
PALLADIUM 0.5% ON ALUMINA
PALLADIUM 0.3% ON ALUMINA
PALLADIUM WIRE: 99.9%, 3N
PALLADIUM 10% ON GRAPHITE
PALLADIUM POWDER (99.95%)
PALLADIUM POWDERED 99+ 5 G
PALLADIUM POWDERED 99+ 1 G
Palladiumonaluminaxpellets
wetted with ca. 53% water)
Pd/C (Palladium on carbon)
Palladium on alumina（0.5%）
Palladium on alumina（0.3%）
Palladium powder, -60 mesh
Palladium powder, GR 99.9%
Palladium, granules, 99.95%
Palladium graphite catalyst
PALLADIUM CALCIUM CARBONATE
PALLADIUM, GRANULES, 99.99%
PalladiumfoilNmmthickcagxmm
PALLADIUM (PALLADIUM BLACK)
Palladium on alumina powder
Palladium on Aluminum oxide
PALLADIUM ROD, 3N5+: 99.95%
PALLADIUM SPONGE: 99.9%, 3N
Palladium10%OnZincCarbonate
Palladium Rod 6 mm diameter
PALLADIUMONPOWDEREDCHARCOAL
PALLADIUM AUF BARIUM SULFATE
Palladium Powder < 60 micron
PALLADIUM, 5% ON CARBON, DRY
Palladium on Resin , reduced
PALLADIUM ON SILICA, REDUCED
PALLADIUM POWDER, 5N: 99.999%
Palladium on alumina catalyst
Palladium Wire/Φ1.0 mm/99.95%
Palladium Wire/Φ0.50mm/99.95%
Palladium Wire/Φ0.25mm/99.95%
Palladiumblacksurfaceareasqmg
PALLADIUM, 10% ON CARBON, DRY
PALLADIUM SPONGE: 99.95%, 3N5
Palladium Nanopowder (Type I)
Palladium, 10% on carbon(wet)
palladium on carbon 1% 10% 5%
Palladium ISO 9001：2015 REACH
5% Palladium on barium sulfate
Palladium Nanopowder (Type II)
Palladium on Mesoporous Carbon
Palladium Wire 1.0 mm diameter
Palladium Wire 0.1 mm diameter
Palladium Wire 0.5 mm diameter
Palladium Black (Metals Basis)
PALLADIUM 1% ON BARIUM SULFATE
PalladiumspongeNbluegraypowder
PALLADIUM ON CALCIUM CARBONATE
PALLADIUM, 5% ON BASO4, REDUCED
PALLADIUM POWDER 20-50 NM 99.9%
PALLADIUM 10% ON BARIUM SULFATE
Palladium Powder 1.2-2.5 micron
Palladium Wire 0.25 mm diameter
Palladium,0.5%onalumina,reduced
PALLADIUM POWDER 10-20 NM 99.9%
Palladium, 5% on barium sulfate
Palladium on barium sulfate（5%）
Palladium on barium sulfate（1%）
Palladium, 5% on alumina powder
Palladium on activated charcoal
Palladium powder, <1 μm, ≥99.9%
Palladium foil, 0.025 mm, thick
Palladium (Single Crystal) <100>
Palladium (Single Crystal) <110>
Palladium (Single Crystal) <111>
Palladium on barium sulfate（10%）
Palladium carbon catalyst PD/C8%
PALLADIUM POWDER -200 MESH 99.9%
Palladium Wire 0.125 mm diameter
Palladium Wire 0.025 mm diameter
PALLADIUM 1% ON BARIUM CARBONATE
Palladium, 5% on barium sulphate
Palladium, Sponge 20 Mesh 99.95%
Palladiumonactivatedcarbonpowder
PALLADIUM 99+ P.A. EMSURE(R) 1 G
PALLADIUM 99+ P.A. EMSURE(R) 5 G
10%Palladium, on activated carbon
palladium coating quality balzers
PalladiuM on carbon hydrogenation
PalladiuM 5% on carbon dry powder
Palladium, 5% on carbon, Type 87L
PALLADIUM POWDER -2 MICRON 99.9+%
PALLADIUM, NIST STANDARD SOLUTION
PALLADIUM, 5% ON ACTIVATED CARBON
Palladium on activated carbon(5%)
Palladium powder, -60 mesh, 99.9%
Palladium rod, dia 6.35mm, 99.95%
10% Palladium on calcium carbonate
PALLADIUM0.3%ONAChemicalbookLUMINA
Palladium on calcium carbonate（5%）
Palladium 5% On Activated Charcoal
Palladium Nanoparticles Dispersion
Palladium, 10% on carbon, Type 487
PALLADIUM STANDARD SOLUTION 100 ML
PALLADIUM STANDARD SOLUTION 500 ML
PalladiuM 10% on Carbon, dry basis
PALLADIUM, 10% ON ACTIVATED CARBON
Palladium Foil/0.05x50x50mm/99.95%
Palladium Foil/0.10x50x50mm/99.95%
Palladium Sheet/0.25x50x50mm/99.95%
Palladium Sheet/0.50x25x25mm/99.95%
Palladium Sheet/1.00x25x25mm/99.95%
Palladium Foil/0.025x50x50mm/99.95%
Palladium powder (99.999%) PURATREM
Palladium on iO‐brane (150mm×150mm)
PalladiumshotNbluegraygranmmanddown
PALLADIUM, FOIL, 0.5MM THICK, 99.9%
PALLADIUM, WIRE, 0.1MM DIAM., 99.9%
PALLADIUM, ROD, 3.1MM DIAM., 99.9+%
PALLADIUM, WIRE, 1.0MM DIAM., 99.9% | [EINECS(EC#)]
231-115-6 | [Molecular Formula]
Pd | [MDL Number]
MFCD03427452 | [Molecular Weight]
106.42 | [MOL File]
7440-05-3.mol |
| Chemical Properties | Back Directory | [Appearance]
Grey Powder | [Melting point ]
1554 °C(lit.)
| [Boiling point ]
2970 °C(lit.)
| [density ]
1.025 g/mL at 25 °C
| [storage temp. ]
Store at RT. | [solubility ]
soluble in aqua regia | [form ]
wire
| [color ]
Silver-gray | [Specific Gravity]
12.03 | [Odor]
Odorless | [Stability:]
Stable. Flammable-fine powder may cause fire or explosion in air. Incompatible with ozone, sodium tetrahydroborate, sulphur, arsenic. | [Resistivity]
9.96 μΩ-cm, 20°C | [Water Solubility ]
INSOLUBLE | [Merck ]
14,6989 | [Exposure limits]
ACGIH: TWA 1 mg/m3
OSHA: TWA 15 mg/m3; TWA 5 mg/m3 | [InChIKey]
KDLHZDBZIXYQEI-UHFFFAOYSA-N | [History]
Discovered in 1803 by Wollaston.
Palladium is found along with platinum and other metals
of the platinum group in deposits of Russia, South Africa,
Canada (Ontario), and elsewhere. Natural palladium contains
six stable isotopes. Twenty-nine other isotopes are recognized,
all of which are radioactive. It is frequently found associated
with the nickel-copper deposits such as those found
in Ontario. Its separation from the platinum metals depends
upon the type of ore in which it is found. It is a steel-white
metal, does not tarnish in air, and is the least dense and lowest
melting of the platinum group of metals. When annealed, it
is soft and ductile; cold working greatly increases its strength
and hardness. Palladium is attacked by nitric and sulfuric acid.
At room temperatures the metal has the unusual property of
absorbing up to 900 times its own volume of hydrogen, possibly
forming Pd2H. It is not yet clear if this a true compound.
Hydrogen readily diffuses through heated palladium and this
provides a means of purifying the gas. Finely divided palladium
is a good catalyst and is used for hydrogenation and
dehydrogenation reactions. It is alloyed and used in jewelry
trades. White gold is an alloy of gold decolorized by the addition
of palladium. Like gold, palladium can be beaten into leaf
as thin as 1/250,000 in. The metal is used in dentistry, watchmaking,
and in making surgical instruments and electrical
contacts. Palladium recently has been substituted for higher
priced platinum in catalytic converters by some automobile
companies. This has caused a large increase in the cost of palladium.
The prices of the two metals are now, in 2002, about
the same. Palladium, however, is less resistant to poisoning by sulfur and lead than platinum, but it may prove useful in
controlling emissions from diesel vehicles. The metal sells for
about $350/tr. oz. ($11/g). | [Uses]
Palladium is a soft white metal found in copper and nickel
ores. The chloride compound of this element was used after
the turn of the century for printing and also in combination
with platinum for printing. | [CAS DataBase Reference]
7440-05-3(CAS DataBase Reference) | [NIST Chemistry Reference]
Palladium(7440-05-3) | [EPA Substance Registry System]
7440-05-3(EPA Substance) |
| Safety Data | Back Directory | [Hazard Codes ]
T,F,Xi | [Risk Statements ]
R61:May cause harm to the unborn child.
R33:Danger of cumulative effects.
R37/38:Irritating to respiratory system and skin .
R40:Limited evidence of a carcinogenic effect.
R41:Risk of serious damage to eyes.
R36/37/38:Irritating to eyes, respiratory system and skin .
R11:Highly Flammable. | [Safety Statements ]
S53:Avoid exposure-obtain special instruction before use .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S24/25:Avoid contact with skin and eyes .
S36:Wear suitable protective clothing .
S22:Do not breathe dust . | [RIDADR ]
UN 3089 4.1/PG 2
| [WGK Germany ]
-
| [RTECS ]
RT3480500
| [Autoignition Temperature]
>1120 °F | [TSCA ]
Yes | [HazardClass ]
4.1 | [PackingGroup ]
III | [HS Code ]
28439090 | [Hazardous Substances Data]
7440-05-3(Hazardous Substances Data) | [Toxicity]
LD50 oral (rat) 200 mg/kg (palladium chloride)
LC50 intratracheal (rat) 6 mg/kg (palladium chloride) |
| Raw materials And Preparation Products | Back Directory | [Raw materials]
Sulfuric acid-->Ammonium hydroxide-->Ammonium chloride-->Chlorine-->Sulfur dioxide-->Sodium chlorate-->Nitrohydrochloric acid | [Preparation Products]
Homovanillic acid-->2-Aminophenylboronic acid-->1-BOC-4-HYDROXY-4-(HYDROXYMETHYL)-PIPERIDINE-->5-Hydroxyindole-->3-AMINO-2,6-DIMETHYLPYRIDINE-->Zalcitabine-->3-PYRIDIN-2-YL-PROPIONIC ACID H2SO4-->1-METHYL-PIPERIDINE-4-CARBOXYLIC ACID-->DIMETHYL METHYLSUCCINATE-->1-(4-AMINO-2,6-DICHLOROPHENOXY)-3-MORPHOLINOPROPAN-2-OL-->2-AMINO-3,5-DICYANOPYRIDINE-->Pyridazin-3-amine-->6-HYDROXYMETHYLINDOLE-->5-AMINOINDOLE HYDROCHLORIDE-->Pyridazine, 3-bromo- (9CI)-->(3R)-(+)-3-(DIMETHYLAMINO)PYRROLIDINE-->cis-1,2-Diaminocyclohexane-->2-ACETAMIDO-5-AMINO-4-PICOLINE-->4-(2-MORPHOLINOETHOXY)-3,5-DICHLOROBENZENAMINE-->N-(4,6-DIMETHYLPYRIMIDIN-2-YL)BENZENE-1,4-DIAMINE-->(3S)-(+)-3-Aminopyrrolidine dihydrochloride-->2,3-Diaminopyridine-->1H-INDAZOL-7-AMINE-->6-Aminoquinoxaline-->3-Amino-4,6-dimethylpyridine-->6-Hydroxyindazole-->7-Hydroxyindole-->3(2H)-Pyridazinone-->2-(4-AMINOPHENYL)ETHYL AMINE 2HCL-->5-AMINOINDAZOLE-->N-METHYL-2-PIPERAZIN-1-YLACETAMIDE-->4-(2-(N-PHENYL-N-ETHYLAMINO)ETHOXY)-3,5-DICHLOROBENZENAMINE-->4-Deoxypyridoxine hydrochloride-->(3R)-(-)-3-Aminopyrrolidine dihydrochloride-->4-BROMO-2-FLUOROBENZYLAMINE-->3-(3,4,5-TRIMETHOXYPHENYL)PROPIONIC ACID-->1,2,3-BENZOTHIADIAZOLE-5-CARBOXYLIC ACID-->4-Aminotetrahydropyran-->2-Quinolinemethanamine-->TETRAHYDRO-3-FUROIC ACID |
| Questions and Answers (Q&A) | Back Directory | [Description]
Palladium was discovered in 1803 by W.H. Wollaston during refining and purification of- platinum metal. This new metal was found in the aqua regia extract of native platinum and was detected in solution after platinum was precipitated. It was removed as ammonium chloroplatinate. Treating this solution with mercurous cyanide precipitated a yellow palladium complex salt. The precipitate was washed and ignited to form palladium metal. Wollaston named the element palladium after the newly discovered asteroid Pallas.
Palladium in nature is always associated with other platinum group metals. Its abundance in earth's crust is estimated at 0.015 mg/kg, about three times more abundant than platinum. Palladium is used mostly in alloys and the majority of its alloys are used for electronics and telecommunications. They are contacts in electrical relays and automatic switching gear. Palladium-gold alloys are applied widely in dentistry and medicine. They are in devices for replacement of damaged bones and joints and as support in porcelain-overlay bridgework. Palladium alloys are used in decoration and jewelry as a substitute for gold. They are used in gems, watch cases and brooches.
One of the most important applications of palladium is to catalyze hydrogenation, dehydrogenation, and petroleum cracking. Such reactions are widely employed in organic syntheses and petroleum refining. Palladium and platinum are installed in catalytic converters in automobiles to cut down the emission of unsaturated hydrocarbon gasses.
| [Chemical properties]
It is a silver-white metal (face-centered cubic crystal). Soluble in aqua regia, hot nitric acid, sulfuric acid, slightly soluble in hydrochloric acid, insoluble in cold water and hot water. | [Uses]
- For the production of catalysts, such as palladium asbestos, sponge and palladium;
- Making electrical instrumentation;
- For the precise alloy production, such as dental materials, watches and surgical instruments;
| [Preparation]
It can be made from the ore with dry process in Industrial production; can also copper, nickel sulfide ore preparation of copper, nickel production process as a by-product as raw materials, made by wet smelting. It can also be obtained from the wet process with the byproduct of copper, nickel production from the copper sulfide ore or nickel sulfide ore.
The wet method is using the residue of extracted nickel and copper as raw materials, adding aqua for extraction, filtration, adding ammonia and hydrochloric acid to react, thus forming the precipitation of ammonium chloropalladate. After refining, filtration, reduction of ammonium chloropalladate with hydrogen 99.95% finished product of palladium can be obtained. | [Reactions]
Among the platinum group metals, palladium is the least noble metal, exhibiting greater reactivity than other metals of the group. The metal forms mostly bivalent compounds, although a small number of tetravalent and a fewer trivalent compounds are known. Palladium exhibits a strong tendency to form complexes, most of which are four-coordinated square planar complexes of the metal in +2 oxidation state. When heated in air or oxygen above 350°C, palladium forms a black oxide, PdO coated over its surface. On further heating to over 790°C, the oxide decomposes back to the metal. Palladium dissolves more oxygen in molten state than in solid form.
Palladium reacts with fluorine and chlorine at 500°C forming its halides, the black PdF3 and the red deliquescent solid PdCl2.
Palladium is attacked by concentrated nitric acid, particularly in the presence of nitrogen oxides. The reaction is slow in dilute nitric acid. Finely divided palladium metal reacts with warm nitric acid forming palladium(II) nitrate, Pd(NO3)2. Hydrochloric acid has no affect on the metal. Reaction with boiling sulfuric acid yields palladium sulfate, PdSO4, and sulfur dioxide.
Palladium readily dissolves in aqua regia forming chloropalladic acid, H2PdCl6. Evaporation of this solution yields palladium(II) chloride, PdCl2.
Palladium absorbs hydrogen over 800 times its own volume over a range of temperature. By doing so, the metal swells, becoming brittle and cracked. Such absorption of hydrogen decreases the electrical conductivity of the metal. Also, such absorption activates molecular hydrogen, dissociating it to atomic hydrogen.
|
| Hazard Information | Back Directory | [Physical properties]
Palladium is the middle element in group 10 of the transition elements (periods 4, 5, and6). Many of its properties are similar to nickel located above it and platinum just below it inthis group.
Palladium is a soft, silvery-white metal whose chemical and physical properties closelyresemble platinum. It is mostly found with deposits of other metals. It is malleable and ductile,which means it can be worked into thin sheets and drawn through a die to form very thinwires. It does not corrode. Its melting point is 1,554°C, its boiling point is 3,140°C, and itsdensity is 12.02 g/cm3. | [Isotopes]
There are 42 isotopes of palladium, ranging from Pd-91 to Pd-124. All but sixare radioactive and artificially produced in nuclear reactors with half-lives ranging from159 nanoseconds to 6.5×10+6 years. The six stable isotopes of palladium and theirproportional contribution to their existence in the Earth’s crust are as follows: Pd-102 =1.02%, Pd-104 = 11.14%, Pd-105 = 22.23%, Pd-106 = 27.33%, Pd-108 = 26.46%,and Pd-110 = 11.72%. | [Origin of Name]
Palladium is named after the asteroid Pallas, which was discovered at
about the same time as the element. Pallas is the name of two mythological Greek figures,
one male and the other female. | [Occurrence]
Palladium is considered a rare metal, making up only about 1 part per 100 million partsof the Earth’s crust. It is considered the 77th most abundant element on Earth, although it is seldom found in pure states. Rather, it is mixed with other metals or in compounds of palladium.
It was originally found in gold ores from Brazil, where the miners thought the gold wascontaminated by what they referred to as “white gold.” Later, it was considered an alloy combinationof palladium and gold.
Deposits of ores containing palladium, as well as other metals, are found in Siberia and theUral Mountains of Russia, Canada, and South Africa, as well as in South America. | [Characteristics]
One of palladium’s unique characteristics is its ability to absorb 900 times its own volumeof hydrogen gas. When the surface of the pure metal is exposed to hydrogen gas (H2), the gasmolecules break into atomic hydrogen. These hydrogen atoms then seep into the holes in thecrystal structure of the metal. The result is a metallic hydride (PdH0.5) that changes palladiumfrom an electrical conductor to a semiconductor. The compound palladium dichloride (PdCl2)also has the ability to absorb large quantities of carbon monoxide (CO). These characteristicsare useful for many commercial applications. Palladium is the most reactive of all the platinumfamily of elements (Ru, Rh, Pd, Os, Is, and Pt.) | [Application]
Palladium is used in the preparation of Palladium catalysts. Palladium based nanomaterials can also be applied in cancer diagnosis and therapy. | [Definition]
ChEBI: Chemical element (nickel group element atom) with atomic number 46. | [Definition]
palladium: Symbol Pd. A soft whiteductile transition element (see alsoplatinum metals); a.n. 46; r.a.m.106.4; r.d. 12.02; m.p. 1552°C; b.p.3140±1°C. It occurs in some copperand nickel ores and is used in jewelleryand as a catalyst for hydrogenationreactions. Chemically, itdoes not react with oxygen at normaltemperatures. It dissolves slowly inhydrochloric acid. Palladium is capableof occluding 900 times its ownvolume of hydrogen. It forms fewsimple salts, most compounds beingcomplexes of palladium(II) with somepalladium(IV). It was discovered byWilliam Woolaston (1766–1828) in1803. | [Production Methods]
Palladium and platinum have been used since 1974 as
catalyst to oxidize carbon monoxide to carbon dioxide in
automobile engines and in hydrocarbon conversion. This use
of palladium results in palladium being emitted as solid
particles with automotive exhaust gases. | [General Description]
We are committed to bringing you Greener Alternative Products, which adhere to one or more of The 12 Principles of Greener Chemistry. This product has been enhanced for energy efficiency. Find details here. | [Hazard]
Palladium is not combustible except as fine powder or dust. Several of palladium’s compoundsare oxidizing agents, and some react violently with organic substances. | [Flammability and Explosibility]
Palladium on carbon catalysts containing adsorbed hydrogen are pyrophoric,
particularly when dry and at elevated temperatures. Palladium on carbon catalysts
prepared by formaldehyde reduction are less pyrophoric than those reduced with
hydrogen. Finely divided carbon, like most materials in powder form, is capable of
creating a dust explosion. | [Industrial uses]
A rare metal, palladium (symbol Pd) is foundin the ores of platinum. It resembles platinum,but is slightly harder and lighter in weight andhas a more beautiful silvery luster. It is onlyhalf as plentiful but is less costly. The specificgravity is 12.10 and the melting point is1552°C. Annealed, the metal has a hardness ofBrinell 40 and a tensile strength of 186 MPa.
It is highly resistant to corrosion and toattack by acids, but, like gold, it is dissolved inaqua regia. It alloys readily with gold and isused in some white golds. It alloys in all proportionswith platinum and the alloys are harderthan either constituent.
Palladium is soft and ductile and can be fabricatedinto wire and sheet. The metal forms ductilealloys with a broad range of elements. Palladiumis not tarnished by dry or moist air atordinary temperatures. At temperatures from350 to 790°C a thin protective oxide forms inair, but at temperatures from 790°C this filmdecomposes by oxygen loss, leaving the brightmetal. In the presence of industrial sulfur-containinggases a slight brownish tarnish develops;however, alloying palladium with small amountsof iridium or rhodium prevents this action.
The major applications of palladium are in theelectronics industry, where it is used as an alloywith silver for electrical contacts or in pastes inminiature solid-state devices and in integratedcircuits. Palladium is widely used in dentistryas a substitute for gold. Other consumer applicationsare in automobile exhaust catalysts andjewelry. | [Environmental Fate]
Routes and Pathways, and Relevant Physicochemicals
Properties
Melting point＝ 1554.9 °C
Boiling point＝ 2963 °C
Solubilities: soluble in aqua regia and fused alkalis; insoluble
in organic acids
Partition Behavior in Water, Sediment, and Soil
Palladium compounds can enter the environment during the
mining and production of platinum group metals and is usually
found with platinum. The mobility of palladium compounds in
soil, therefore, is similar to that of platinum compounds. In soil, mobility depends on low pH and high chloride concentration.
The reactions of palladium compounds in water are depending
on pH level, redox potential, and ligand availability. It usually
has low affinity for hard ligands, such as fluoride and oxygen.
Palladium compounds are ionic; therefore, volatilization from
water and soil surfaces is not expected to be an important
environmental fate process.
Environmental Persistency
Palladium occurs in the earth’s crust at the concentration of
w0.2 ppm. This group of metals can be transferred from the
earth’s interior, where they are mostly concentrated in high
volume, to the lithosphere by volcanic activity. Environmental
levels of palladium in water, soil, and ambient air are not high.
Palladium, as a metal, tends to persist in the upper soil layer.
Long-Range Transport
Transfer from water column to sediment is assumed through
exchange, complexation, or precipitation reactions.
Bioaccumulation and Biomagnifications
Palladium has low to moderate bioaccumulation in terrestrial
and aquatic organisms, respectively. | [storage]
In
particular, palladium on carbon should always be handled under an inert atmosphere
(preferably argon), and reaction vessels should be flushed with inert gas before the
catalyst is added. Dry catalyst should never be added to an organic solvent in the
presence of air. Palladium on carbon recovered from catalytic hydrogenation
reactions by filtration requires careful handling because it is usually saturated with
hydrogen and will ignite spontaneously on exposure to air. The filter cake should
never be allowed to dry, and the moist material should be added to a large quantity
of water and disposed of properly. | [Toxicity evaluation]
Palladium ions, because of their ability to form strong
complexes with both organic and inorganic ligands, have the
potential to disturb cellular equilibria and interact with
macromolecules functional groups, such as proteins or DNA/
RNA, which interrupt various cellular processes. Palladium and
its compounds also have the ability to inhibit many enzymatic
activities as shown in in vitro and in vivo studies. These enzymes
include prolyl hydroxylase, creatine kinase, aldolase, succinic
dehydrogenase, carbonic anhydrase, and alkaline phosphatase.
Palladium, furthermore, has the capability of occupying
different oxidation states, which in turn may have different
effects. The ability of Pd4+ ions to change their oxidation states
to Pd2+ may also contribute to harmful effects. Studies have
shown that exposure to Pd2+ may disturb the organisms’
energy metabolism, acid–base, and electrolytic equilibria. Also,
exposure to high concentration of palladium during developmental
period may retard fetal growth and development. | [Incompatibilities]
Catalysts prepared on high surface area supports are highly active and readily cause
ignition of hydrogen/air and solvent/air mixtures. Methanol is notable for easy
ignition because of its high volatility. Addition of catalyst to a tetrahydroborate
solution may cause ignition of liberated hydrogen. | [Waste Disposal]
Excess palladium on carbon and waste material containing this substance should be covered in water,
placed in an appropriate container, clearly labeled, and handled according to your institution's waste
disposal guidelines. |
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