What is Catalyst Lifetime — and why does it matter?

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A catalyst's lifetime — how many reaction cycles it can be reused before its activity falls below a useful threshold — is a central green chemistry concern. Under Principle 9, catalysis is preferred over stoichiometric reagents because catalysts are not consumed in the reaction. But that advantage is only realised if the catalyst can be recovered and recycled efficiently. A catalyst that deactivates after a single cycle may still generate more waste than the stoichiometric reagent it replaces.

GoalMaximise the number of productive cycles before catalyst retirement, reducing the amount of precious or hazardous metal waste generated per unit of product.

WhyLonger catalyst lifetime means lower cost-per-turnover, less metal waste, and a lower effective E-factor contribution from the catalyst. It rewards process design that protects the active site.

HowDesign robust ligands, choose mild conditions, avoid catalyst poisons, use immobilised or heterogeneous systems for easy recovery, and monitor activity each cycle.

Key metrics

$$\text{TON}_{\text{cycle}\,n} = \frac{n_{\text{product},n}}{n_{\text{catalyst}}}$$

Symbol	Term	Units
$\text{TON}_{\text{cycle}\,n}$	Turnover number for cycle n	mol mol⁻¹ (dimensionless)
$n_{\text{product},n}$	Moles of product isolated in cycle n	mol
$n_{\text{catalyst}}$	Moles of catalyst (constant — same batch reused)	mol

$$A_n = \frac{\text{TON}_n}{\text{TON}_1} \times 100\%$$

Symbol	Term	Units
$A_n$	Activity retention at cycle n (relative to cycle 1)	%

When catalyst deactivation follows first-order kinetics (the most common model for gradual deactivation by sintering, poisoning, or leaching), activity decays exponentially with cycle number:

$$A_n = A_0 \cdot e^{-k_d \cdot (n-1)}$$

Symbol	Term	Units
$A_0$	Initial activity (= 100% at cycle 1)	%
$k_d$	Deactivation rate constant (fitted from data)	per cycle
$n$	Cycle number	—

$$t_{1/2} = \frac{\ln 2}{k_d}$$

Symbol	Term	Units
$t_{1/2}$	Half-life: cycles until activity reaches 50% of initial	cycles
$k_d$	First-order deactivation rate constant	per cycle

This tool fits $k_d$ to your experimental data using linear regression on $\ln(A_n)$ vs cycle number. The goodness-of-fit (R²) is reported alongside the extrapolated half-life and productive lifetime. If fewer than three data points are entered, only cumulative TON and per-cycle statistics are reported — the deactivation model requires at least three cycles.

Strengths and limitations

Strengths

Directly measures real-world catalyst recyclability
Cumulative TON captures the full economic and environmental value of the catalyst
First-order model is interpretable and predictive — enables rational catalyst design
Works for heterogeneous, homogeneous, and enzymatic catalysts (activity-based, not mechanism-specific)
Half-life allows direct comparison across catalyst systems

Limitations

Requires experimental multi-cycle data — cannot be determined a priori
First-order model may not fit all deactivation mechanisms (e.g. sudden poisoning, or induction periods)
Does not capture selectivity loss — activity retention ≠ selectivity retention
TON per cycle depends on reaction conditions; only comparable within the same protocol
Does not account for regeneration or reactivation between cycles

Catalyst Lifetime in context

Metric	What it measures	Stage
TON (Turnover Number)	Moles product per mole catalyst — single-run efficiency	Experimental
TOF (Turnover Frequency)	TON per unit time — rate of catalysis	Experimental
Catalyst Lifetime	Cycles of productive use; half-life; cumulative TON across all cycles	Experimental (multi-cycle)
E-factor	Mass waste per mass product — includes catalyst waste on deactivation	Experimental
Activity Retention	% of initial activity remaining after n cycles	Experimental

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Experiment details

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Experiment / reaction name

Researcher(s)

Date

Lab / institution

Reaction type

Solvent

Temperature

Catalyst recovery method

Reference / DOI

Notes

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Catalyst parameters

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Enter the catalyst used in each recycling run. The same physical batch of catalyst is assumed to be recovered and reused. If you regenerate or top up the catalyst between cycles, note this in the experiment details above.

Catalyst name

Catalyst amount (mmol) Moles of active metal or active site. Enter in mmol — the calculator converts internally.

Product molecular weight (g mol⁻¹) Used to convert product mass (g) entered per cycle into moles for TON calculation.

Minimum activity threshold (%) Productive lifetime is reported as the extrapolated cycle at which activity falls below this value. Default: 50% (= half-life).

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Cycle data

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Enter the mass of product isolated for each recycling cycle using the same catalyst batch. Cycle 1 is the fresh catalyst run — it sets the 100% activity baseline. Add one row per cycle in sequence. If you have yield % instead of product mass, use the mass of product after workup.

Cycle	Product mass (g)	TON (cycle)	Activity (%)	Notes

Σ Cumulative TON — total turnovers across all cycles

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Results

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Cumulative TON

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total turnovers

Half-life

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cycles (extrapolated)

Productive Lifetime

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cycles to threshold

Deactivation Rate k_d

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per cycle (R² = —)

Activity retention at last measured cycle (higher is better)

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0%25%50%75%100%

Activity retention per cycle

TON per cycle & cumulative TON

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Detailed breakdown & interpretation

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Cycle	Product mass (g)	TON (cycle)	Activity (%)	Model fit (%)	Residual	Visual
Enter catalyst parameters and cycle data above to see breakdown.

Interpretation

Enter catalyst parameters and at least two cycles of data to generate an interpretation.

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Save & load sessions

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Sessions are stored in your browser only. No data leaves your device.

No saved sessions yet.

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Export

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Export your Catalyst Lifetime analysis as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.

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Where can I read more?

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References are sorted alphabetically by first author.

P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998. ISBN 978-0-19-850698-0. — Original statement of the 12 Principles; Principle 9 frames catalysis as a key tool for waste reduction.
I. P. Beletskaya and A. V. Cheprakov, Chem. Rev., 2000, 100, 3009–3066. DOI. — Comprehensive review of palladium-catalysed C–C coupling; discusses catalyst stability and recycling.
G. Busca, Heterogeneous Catalytic Materials, Elsevier, 2014. ISBN 978-0-444-59524-9. — Covers catalyst deactivation mechanisms: sintering, poisoning, coking, and leaching.
R. H. Crabtree, Chem. Rev., 1995, 95, 987–1007. DOI. — Homogeneous catalyst deactivation by cluster and colloid formation; context for TON limitations.
H. S. Fogler, Elements of Chemical Reaction Engineering, 4th edn, Prentice Hall, 2005. — Standard reference for first-order catalyst deactivation kinetics and half-life derivation.
R. A. Sheldon, Green Chem., 2018, 20, 3899–3914. DOI. — Metrics for sustainable catalysis; discusses TON, TOF, and catalyst lifetime in the green chemistry context.

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Contributors

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Roles follow the CRediT taxonomy (Contributor Roles Taxonomy), adapted for educational software. Hover a contributor's name for a summary, or a column header for the definition of that role.

Contributor

This portal was built with the assistance of a large language model (Claude, Anthropic), which was used to generate and refine code, articulate and structure contributed ideas within the defined page format, and support iterative design decisions. All scientific content, conceptual frameworks, pedagogical choices, and final outputs were directed, reviewed, and verified by the contributors listed above.

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How do I cite this page?

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If you use this tool in teaching or published work, please cite the DodecaGreen portal as the source.

Reference

BibTeX

Catalyst Lifetime calculator.