d-Block Catalysts in Industrial and Real-World Processes
Transition metals and their compounds are the working catalysts behind a huge range of industrial and everyday processes. These matching-style questions come down to memorising a handful of specific, correctly-paired catalyst-and-process combinations, and being alert for one classic detail swapped out in each wrong pairing.
Catalyst-Formula Matching: Fenton, Adams, Wilkinson and Ziegler-Natta Reagents is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Ziegler-Natta: the catalyst for polymerising simple alkenes
Monomers with two carbon atoms joined by one double bond (ethylene and its simple substituted analogues, the general class of alkenes) are polymerised industrially using a Ziegler-Natta catalyst system: titanium tetrachloride (TiCl4) combined with an alkylaluminium compound (classically triethylaluminium or trimethylaluminium, Al(CH3)3 or Al(C2H5)3). This catalyst system allows controlled, stereoregular polymerisation of alkenes into high-density polyethylene and related polymers, and it is specifically a TITANIUM-plus-ALUMINIUM combination — not vanadium-based (V2O5, which belongs to the Contact process instead) and not a boron-aluminium mixture.
Four catalyst-process pairings worth memorising exactly
Several catalysts are tied to one very specific industrial process each, and exam incorrect-match questions usually swap in a plausible-sounding but wrong catalyst: V2O5 (vanadium pentoxide) catalyses the Contact process (oxidation of SO2 to SO3, the key step in industrial sulfuric acid manufacture) — correctly matched. CuCl2 (copper(II) chloride) catalyses the Deacon process (oxidation of HCl to Cl2 using atmospheric oxygen) — correctly matched. Finely divided NICKEL (Ni), not iron, catalyses the hydrogenation of vegetable oil to ghee/vanaspati (this is the one classic wrong pairing to watch for: iron belongs to the Haber process for ammonia synthesis, not to oil hydrogenation). TiCl4 + Al(CH3)3 correctly describes the Ziegler-Natta catalyst, as covered above.
Matching named reagents and catalysts to their correct formulas
Fenton's reagent is FeSO4 + H2O2 (an iron(II) salt combined with hydrogen peroxide, generating hydroxyl radicals, used in advanced oxidation processes) — correctly matched. Adams' catalyst is PtO2 (platinum dioxide, which is reduced in situ to finely divided platinum metal, used for hydrogenation reactions) — correctly matched. Wilkinson's catalyst is [RhCl(PPh3)3] (a rhodium(I) complex used for homogeneous hydrogenation) — correctly matched. The Ziegler-Natta catalyst, however, is TiCl4 (or TiCl3) plus a trialkylALUMINIUM compound like Al(C2H5)3 — NOT a triethylBORON compound; a formula written as (C2H5)3B + TiCl3 swaps aluminium for boron, which is the wrong pairing to flag.
Common mineral names and descriptions can all be correct at once
Not every which-is-incorrectly-matched question has a genuinely wrong pairing hidden in it — sometimes every option given is correct, and the right answer is none of these. Bauxite is correctly Al2O3.xH2O (hydrated aluminium oxide, the principal ore of aluminium). Philosopher wool (lana philosophica) is a traditional name correctly referring to zinc oxide, ZnO, historically produced by burning zinc metal in air, which yields a light, wool-like white solid. Malachite is correctly described as a green pigment (a basic copper carbonate mineral, Cu2CO3(OH)2, historically used as a green pigment and as a minor ore of copper). When every given pairing checks out, the correct answer is that none of them is incorrectly matched — do not force a wrong answer onto a set of statements that are all actually true.
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- ✓Ziegler-Natta catalyst = TiCl4 (or TiCl3) + a trialkylaluminium compound, used for controlled alkene polymerisation
- ✓V2O5 catalyses the Contact process (SO2 to SO3); CuCl2 catalyses the Deacon process (HCl to Cl2)
- ✓Finely divided NICKEL (not iron) catalyses vegetable oil hydrogenation to ghee; iron belongs to the Haber process instead
- ✓Fenton's reagent = FeSO4 + H2O2; Adams' catalyst = PtO2; Wilkinson's catalyst = [RhCl(PPh3)3]
- ✓A Ziegler-Natta formula written with boron instead of aluminium (e.g. (C2H5)3B + TiCl3) is the wrong pairing to flag
- ✓Not every matching question hides a wrong pair — if every statement checks out, none can be the correct answer
Do not default to picking iron as the catalyst for vegetable-oil hydrogenation just because iron is a familiar, heavily-tested d-block catalyst (from the Haber process). The oil-to-ghee hydrogenation specifically uses finely divided NICKEL — mixing up which catalyst belongs to which named industrial process is exactly what these matching questions test.
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