Metals, Earth-abundant

The element was discovered by Klaproth in 1803 and also in the same year by Berzelius and Hisinger. It is named after the asteroid Ceres. Cerium is found in several minerals often associated with thorium and lanthanum. Some important minerals are monazite, aUanite, cerite, bastnasite, and samarskite. It is the most abundant element among aU rare-earth metals. Its abundance in the earth s crust is estimated to be 66 mg/kg, while its concentration in sea water is approximately 0.0012 microgram/L. 

Ruthenium occurs in nature natively, found in minor quantities associated with other platinum metals. Its abundance in the earth s crust is estimated to be 0.001 mg/kg, comparable to that of rhodium and iridium. 

Candidate Metal Oxides, Abundance of their Metals in Earth s Crust, their Solubility, and CBPC Forming Temperature. 

In general, Y and the heavier lanthanides, Gd to Lu, are less abundant than the lighter lanthanides. La to Eu. However, there are two further complicating factors one is that the elements with even atomic number are more abundant than those of odd atomic number, reflecting the greater stability of such nuclei. Secondly, some ores (e.g. bastnasite, monazite) are richer in the lighter metals while others (e.g. xenotime) have more of the heavier metals. The abundance of yttrium in the Earth s crust is 31 ppm while the total abundance of the lanthanides is some 180 ppm cerium is the most abundant (66 ppm), while thulium and lutetium are the rarest (0.5 and 0.8 ppm, respectively). 

In addihon to the more generally reachve group 3 elements, examples of group 4 metals with amidate, pyridonate, and sulfonamidate ligands have been reported for ROP of cyclic esters. Such group 4 metals, and in particular titanium, are attractive due to their low cost, low toxicity, and high earth abundance. Furthermore, such complexes are known to be more robust than rare earth element complexes and thus less sensitive to the purity of the monomeric feedstock that is used for ROP. 

Sources and Production Potassium is highly reactive and does not occur in nature as a free metal. The abundance of potassium in the 16 km-thick Earths crust - mainly in silicates (feldspars, micas) - is 25.9 g kg k In the frequency list of the elements, potassium occupies seventh place. Its abundance in sea vater is almost as great, due to the veathering of potassium-containing minerals. After veathering of the rocks, potassium is bound by the calcium zeolites of the soils, and only part of it reaches the sea (0.38 g sea water). 

Biosorption is a key technology for the benign recovery of diffuse elements from liquid effluents and hydrometallurgy processes. During the capture of metals via biosorption the reduction of the metal down to nanoparticles is commonly observed. One such example is the use of starch-derived carbonaceous mesoporous materials (Starbon ) for the selective adsorption and recovery of critical metals (Au , Pt and Pd ") from a mixture containing Earth-abundant elements (Ni ", Cu " and Zn ") with the... 

It is vital that we seek to maximise the metals catalytic activity and recover 100% of elements from catalytic processes at both the end of reaction and end of life (the only exception may be carbon that can be burnt for energy production at end of life). Development and application of Earth-abundant catalysts for a wider range of catalytic applications is possible in the midterm. However, the long-term and ideal scenario would be that even critical elements can be used as sustainable catalysts if total recoveiy from anthropogenic cycles is guaranteed. The concept of elemental sustainability for catalysis is likely to become increasingly important in the future. Now is the time for producers and users alike to progress to circular economies and embrace sustainable catalysis. 

Contained within this book are various chapters that review the possibilities for the sustainable use of catalysts in our chemical industiy. Earth abundant metals are discussed in Sustainable Catalysis With Non-endangered Metals, Parts 1 and 2, while the options for organocatalysis are discussed in Sustainable Catalysis Without Metals or Other Endangered Elements, Parts 1 and 2. The future chemical industiy cannot survive by the use of just one of the above catalyst classes, but will require the flexibility and versatility of both. An important aspect of sustainable catalysis that is also vital for the long-term security of elements is ensuring that we establish improved methods of catalyst recovery and reuse. 

Light harvesting with Earth abundant d-block metals Development of sensitizers in dye-sensitized solar cells (DSCs) 13CCR3089. 

Enzymes have long been known to be efficient catalysts [1-3]. In particular, they are admired for selectivity, fast rates, and low activation energies. When considering applications that require sustainability and scalability, enzymes also have the advantage of being constructed exclusively from earth-abundant, bioavailable materials. Thus metalloenzymes typically employ only earth-abundant metals... 

Another earth abundant metal (30 times more than cobalt), extensively investigated by several research groups, is manganese, since it is present in the OEC of Photosystem II. 

Once electrochemically or chemically activated, this complex undergoes a stepwise loss of four electrons and four protons, producing an intermediate reactive species able to oxidizes water. Unfortunately, the blue dimer loses its catalytic efficiency after few cycles, due to the degradation of the organic ligands. However, its discovery paved the way to the development of a variety of molecular water oxidation catalysts, most of them still based on ruthenium centers, but also on iridium, as well as on earth abundant and cheap metals, such as manganese, iron, and cobalt. " ... 

Most recently, Pt-based electrocatalysts with novel nanostructures such as nanowire, nanotube, hollow, core-shell, and nanodendrite structures have been investigated [71-74, 101]. One-dimensional ternary PtRuM (M = Ni, Co, and W) nanowire catalysts were synthesized, and these catalysts outperform Pt-Ru commercial catalyst and have a low noble-metal content due to the incorporation of an Earth-abundant element [101]. 

Heat-treated non-precious metal catalysts, synthesized from earth-abundant elements, are capable of catalyzing the ORR and efficiently generating electricity from fuels via a direct electrochemical conversion. Carbon-nitrogen precursors, supports, and in situ formed graphitized carbon play an important role in the catalyst performance. 

Biochemistry is only understandable in terms of the symbiotic use of some 25 essential elements, most of which are metals. The abundances of chemical elements were preordained by the physical events following the Big Bang even down to the level of the composition of the earth s crust. Biological systems are able to utilize the redistribution of energy within the solar system to readjust element distribution on the earth s local scale. They do this because of the pressures of natural selection that only allow those species with highly effective chemistry to survive. 

In general, earth-abundant elements should be the dominant transition metals used if a low-cost positive electrode is desired. Both iron and manganese are abundant and inexpensive transition metals for intercalation materials. Comparison of the iron... 

Nonetheless, single-site catalysts did a very significant contribution to the field by involving other late transition metals. In addition to cobalt, nickel , and copper, iron and iridium have yielded a larger number of robust and active molecular catalysts for water oxidation, especially with the latter metal. Iron catalysts are of high relevance, due to the low toxicity and earth abundance of this metal. 

Until recently, C—H functionalization reactions have relied heavily on expensive noble transition-metal catalysts. In the past 10 years, there has been a rise in the interest of low-valent cobalt catalysts for C—H functionalization. These catalysts are earth-abundant, green, and can generally be used under milder reaction conditions than their noble transition-metal catalyst counterparts. 

Metals are unevenly distributed throughout Earth s crust. All the metals together compose about 25% of the mass of Earth s crust, but just a few key metals are abundant enough to each individually compose more than 1% of the crust. 

Electrochemical deposition (ECD) has been a technique for material synthesis since Luigi Brugnatelli first electroplated gold in 1805. After this historic achievement, ECD has advanced to include the deposition of other metals and alloys through the use of earth-abundant metal salts. In more recent times, metal oxides," -" metal sulfides," semiconductors, - and conductive... 

On the basis of the aforementioned analyses, we had previously [25] hypothesized that a catalyst with a combination of earth-abundant transition metal iron... 

On the basis of these analyses, we hypothesized the use of an earth-abundant transition-metal complex containing a non-redox-active metal center and redox-active (non-innocent) ligand as a catalyst. We demonstrated our prediction on [(PDl)Ca(THF)3], where PDI is a non-innocent pyridine-2,6-diimine ligand, and the catalyzed benzyhc (of the MeCH2Ph substrate) C-H bond alkylation by unsubstituted and diphenyl (termed the iio or-(io or)-substituted diazocarbene precursors, N2CH2 and N2CPh2. 

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