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.
Ziegler-Natta Catalyst for Alkene Polymerisation 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.
OlympIQ exam lens
- ✓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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