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Hydrogenation Catalysts
Published in Alvin B. Stiles, Theodore A. Koch, Catalyst Manufacture, 2019
Alvin B. Stiles, Theodore A. Koch
The foregoing procedure can be modified to include a support by slurrying a support such as kieselguhr or alumina hydrate in the slurry called for in step 1. The procedure can also be modified to produce an iron chromite, cobalt chromite, zinc chromite, nickel chromite, or manganese chromite, and other spinels can be produced by substituting the appropriate ion for the copper. Mixed spinels such as zinc-copper, zinc-manganese, cadmium-copper, etc., can also be produced in this manner. Zinc-copper chromites are active methanol synthesis catalysts. The general procedure given above produces spinels that have excellent properties for many reactions.
Synthesis and characterisation of nanosized spinel particles of nickel-doped iron chromite
Published in Philosophical Magazine Letters, 2021
Malika Rani, Kiran Batool, Ayesha Younus, Atta Ullah Shah, Arshad Mehmood, Rubia Shafique, Shamim Khan, G. Murtaza, R. Neffati
XRD analysis provides details about a sample’s crystal structure and phases [37]. The iron chromite crystalline structure represented by its diffractogram is shown in Figure 1. The pattern is qualitatively similar to that of other magnetite nanoparticles as previously reported, with the highest Bragg peaks found at 77.853 and 81.853 degrees and the reflection plane being (311) [16, 38, 39]. According to this, iron chromite crystallizes as a single phase. Iron chromite possess a cubic spinel structure with Fd-3 m space group and lattice parameters a = b = c of around 8.3 Å and particle sizes of 39 nm to 71 nm. In the case of nickel-doped samples, the peaks positioned at 2θ = 30, 30.5, 35, 35.5, 40.5, 45.5, 50.5, and 55.5 degrees. The lattice parameters of the doped sample are 8.3 and 8.4 Å respectively with an average crystallite size of 47 nm as depicted in Table 2.
Microwave reduction of Black Thor chromite ore
Published in Canadian Metallurgical Quarterly, 2018
Chromite ore is the primary source of chromium, which is a strategic metal and it is widely used as an alloy addition in steels, in particular, stainless steels. Since chromite ore contains both iron and chromium, mainly as iron chromite (FeCr2O4), then during carbothermic reduction, a ferrochromium alloy is obtained. It is commercially produced by carbothermic reduction in a submerged arc furnace [1]. The reduction behaviour of chromite ores has been studied extensively [2–4]. Chromite ore consists of a series of spinels of chromium (III) oxide with magnesium oxide (MgO), aluminium oxide (Al2O3), and/or iron (II) oxide (FeO). The reduction temperature required depends on the stabilities of these spinels. Iron chromite is usually the major spinel and is the least stable. At temperatures around 1150°C, iron chromite reacts with carbon as follows: [3]