chemistry

Phillips catalyst

Phillips catalyst is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Phillips catalyst rather than just read about it. In short: The Phillips catalyst, or the Phillips supported chromium catalyst, is the catalyst used to produce approximately half of the world's polyethylene. A heterogeneous catalyst, it consists of a chromium oxide supported on silica gel.

Key takeaways

Phillips catalyst belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Phillips catalyst to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Phillips catalyst from memory before moving on to harder problems.

Reference excerpt

The Phillips catalyst, or the Phillips supported chromium catalyst, is the catalyst used to produce approximately half of the world's polyethylene. A heterogeneous catalyst, it consists of a chromium oxide supported on silica gel. Polyethylene, the most-produced synthetic polymer, is produced industrially by the polymerization of ethylene:

n C2H4 → (C2H4)n Although exergonic (i.e., thermodynamically favorable), the reaction requires catalysts. Three main catalysts are employed commercially: the Phillips catalyst, Ziegler–Natta catalysts (based on titanium trichloride), and, for specialty polymers, metallocene-based catalysts.

Preparation and mechanism of action The Phillips catalyst is prepared by impregnating high surface area silica gel with chromium trioxide or related chromium compounds. The solid precatalyst is then calcined in air to give the active catalyst. Only a fraction of the chromium is catalytically active, a fact that interferes with elucidation of the catalytic mechanism. The active catalyst is often depicted as a chromate ester bound to the silica surface. The mechanism for the polymerization process is the subject of much research, the central question being the structure of the active species, which is assumed to be an organochromium compound. Robert L. Banks and J. Paul Hogan, both at Phillips Petroleum, filed the first patents on the Phillips catalyst in 1953. Four years later, the process was commercialized.

References

Illustrations

Worked examples

Example 1 — a first encounter with Phillips catalyst

Start with the simplest possible case. Write down what Phillips catalyst claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Phillips catalyst before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Phillips catalyst ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Phillips catalyst

In research: Phillips catalyst appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Phillips catalyst in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Phillips catalyst is common in secondary-school and first-year university syllabi. It links to neighbouring topics Catalysts, Chromium(VI) compounds, Chromium–oxygen compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Phillips catalyst outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Phillips catalyst in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Phillips catalyst means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Phillips catalyst out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Phillips catalyst in simple terms?

Why does Phillips catalyst matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Phillips catalyst?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Phillips catalyst.