Titanium crustal abundance

The extraction of metals fundamentally relies on their availability in nature. Three terms are important while one refers to availability. One is the crustal abundance and the other two are the terms resources and reserves. The average crustal abundance of the most abundant metals, aluminum, iron and magnesium, are 8.1%, 5.0% and 2.1% respectively. Among the rare metals titanium is the most abundant, constituting 0.53% of the Earth s crust No metal can be economically extracted from a source in which its concentration is the same... 

However, most of the available metal-based eatalysts for ROP and a-olefin polymerisation suffer from inherent toxicity, low abundance, high price and are listed as endangered elements, which is in contradiction with their application in green and sustainable procedures for polymer synthesis. In line with sustainable catalyst development, titanium is nontoxic (no known biological role), readily accessible and an abundant element (crustal abundance of 4136 ppm with the lowest supply risk searcity factor is about 2.5/8.5) making this element one of the most attraetive metals for use in sustainable polymerisation catalysis. 

Titanium, which comprises 0.63% (i.e. 6320 ppm) of the earth s crustal rocks, is a very abundant element (ninth of all elements, second of the transition elements), and, of the transition elements, only Fe, Ti and Mn are more abundant than zirconium (0.016%, 162 ppm). Even hafnium (2.8 ppm) is as common as Cs and Br. 

The abundances in the Earth s crust of both the d-block transition metals and the f-block inner transition metals vary considerably, as shown in Table 1.2. Iron is the most common of the transition metals (6.30% by mass of the crustal rocks) and this reflects the high yield of iron from element synthesis reactions in stellar supernovae. Titanium (0.66%) and manganese (0.11%) are also quite abundant, but some of the heavier... 

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