Catalyst Longevity Research Articles

General Strategy for Preparation of Carbon-Nanotube-Supported Nanocatalysts with Hollow Cavities and Mesoporous Shells

Hollow-structured mesoporous catalysts (HMCs) that comprise catalytically active cores, interior reaction space, and permeable shell(s), can bring new opportunities for high-efficiency catalysis. Nevertheless, all the existing HMCs are limited to small spherical yolk–shell type configuration (i.e., zero-dimensional (0D) structure). To include more active cores and to add new merits to the HMCs, in this work, we report a general strategy for preparation of complex one-dimensional (1D) HMCs, in which carbon nanotubes (CNTs) serve as a backbone to support catalytic components and mesoporous silica and/or microporous metal–organic frameworks (MOFs; e.g., ZIF-8) or transition-metal oxides (e.g., Nb2O5) act as membrane-like shells for molecular screening, catalyst protection, and surface functionality. Several types of catalytic nanoparticles (e.g., noble metals Au, Pd, and Au–Pd alloy; and transition metal oxides Co3O4, ZnO, and TiO2) have been anchored onto the CNTs and encapsulated or sheathed with the mesoporous silica shell. Concerning their workability, we have further tested the CNT-based HMCs for selective oxidation of benzyl alcohol to benzaldehyde. Intriguingly, both shell porosity and interior space of catalysts exert significant impacts on benzyl alcohol conversion, benzaldehyde selectivity, and the catalyst longevity. Conceptually, such 1D HMCs can be viewed as linearly integrated 0D HMCs, but they can significantly include more catalytic nanoparticles and enhance catalyst–support interaction, which adds another dimension for the design and synthesis of HMCs.

Hydrophenylation of ethylene using a cationic Ru(ii) catalyst: comparison to a neutral Ru(ii) catalyst

Charge neutral Ru(II) complexes of the type TpRu(L)(NCMe)Ph [Tp = hydridotris(pyrazolyl)borate; L = CO, PMe3, P(OCH2)3CEt or P(OCH2)2(OCCH3)] have been previously reported to catalyze the hydrophenylation of ethylene (Organometallics, 2012, 31, 6851–6860). However, catalyst longevity for the TpRu(L)(NCMe)Ph complexes is inhibited by competitive ethylene C–H activation. For example, ethylene C–H activation limits catalysis using TpRu(P(OCH2)3CEt)(NCMe)Ph to a maximum of 20 turnover numbers for conversion of benzene and ethylene to ethylbenzene. In contrast, reaction of the cationic Ru(II) complex [(HC(pz5)3)Ru(P(OCH2)3CEt)(NCMe)Ph][BAr′4] [HC(pz5)3 = tris(5-methyl-pyrazolyl)methane; BAr′4 = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate] (0.025 mol% relative to benzene) in benzene with C2H4 (15 psi) at 90 °C gives 565 turnover numbers of ethylbenzene after 131 hours. The production of 565 turnovers of ethylbenzene corresponds to an approximate one-pass 95% yield with ethylene is the limiting reagent and is a 28-fold improvement compared to the charge neutral catalyst TpRu(P(OCH2)3CEt)(NCMe)Ph. Under identical conditions, the activity of [(HC(pz5)3)Ru(P(OCH2)3CEt)(NCMe)Ph][BAr′4] is only 1.3 times less than TpRu(P(OCH2)3CEt)(NCMe)Ph, but the increased stability of the cationic Ru(II) catalyst allows reactivity at much higher temperatures (up to 175 °C) and significantly enhanced rates.

Catalytic decomposition of toluene using a biomass derived catalyst

Pine bark biochar generated by slow pyrolysis (950°C) was used as a low cost catalyst to decompose toluene (model tar compound) over a temperature range of 600–900°C. Relative to thermal cracking, fractional toluene conversion increased from 13 to 94% when increasing temperatures from 600 to 900°C (2500ppmv, SV=0.76s−1, 3.8g catalyst) and Arrhenius analysis indicated an activation energy of 91kJ/mol, comparable to that of synthetic catalysts (e.g., 80.24kJ/mol for Ni/Mayenite and 196kJ/mol for olivine) and lower than that of thermal cracking (356kJ/mol). The reaction rate for toluene decomposition increased linearly from 550 to 700°C with a concentration range of 1000–4600ppmv indicating a first order rate law with respect to toluene. Benzene was detected as a potential intermediate in the decomposition of toluene with selectivity ranging from 0 to 28% at temperatures from 600 to 900°C respectively, and its formation increased with increasing toluene conversion. Toluene conversion ranged between 40 and 95% with benzene selectivity from 0 to 20% at 800°C during catalyst longevity studies of 6days. These results indicate that biochar generated from slow pyrolysis of pine bark at high temperature can be used as a low cost catalyst for tar removal from syngas. However, the tar removal rates using the biochar catalyst were lower than that of olivine and nickel based catalysts indicating the need to increase catalytic activity.

Back Cover: Industrial RuO2‐Based Deacon Catalysts: Carrier Stabilization and Active Phase Content Optimization (ChemCatChem 3/2013)

Stability is the key! The cover picture shows the technical RuO2/SnO2-Al2O3 catalyst (2 mm pellets) for the gasphase oxidation of HCl to Cl2. This reaction is an attractive route to valorise byproduct HCl streams in the chemical industry and has been experiencing a strong revival since recent discoveries of durable catalytic materials have broken through to pilot and plant scales. In their Full Paper on p. 748 ff., J. Pbrez-Ramrez, T. Schmidt, and co-workers reveal the stabilizing effect of the nanocrystalline alumina binder on the tin oxide support. The fundamental understanding of this stabilization secures the longevity of the industrial catalyst and has enabled a four-fold decrease in the ruthenium content while maintaining a high specific activity.

The Role of the Alcohol and Carboxylic Acid in Directed Ruthenium‐Catalyzed C(sp3)H α‐Alkylation of Cyclic Amines

A general directed Ru-catalyzed C(sp(3))-H α-alkylation protocol for piperidines (less-reactive substrates than the corresponding five-membered cyclic amines) has been developed. The use of a hindered alcohol (2,4-dimethyl-3-pentanol) as the solvent and catalyst activator, and a catalytic amount of trans-1,2-cyclohexanedicarboxylic acid is necessary to achieve a high conversion to product. This protocol was used to effectively synthesize a number of 2-hexyl- and 2,6-dihexyl piperidines, as well as the alkaloid (±)-solenopsin A. Kinetic studies have revealed that the carboxylic acid additive has a significant effect on catalyst initiation, catalyst longevity, and reverses the reaction selectivity compared with the acid-free reaction (promotes alkylation versus competing alkene reduction).

Hierarchical zeolites prepared by organosilane templating: A study of the synthesis mechanism and catalytic activity

The crystallization of hierarchical ZSM-5 in the presence of the organosilane octadecyl-dimethyl-(3-trimethoxysilyl-propyl)-ammonium chloride as the mesoporogen was investigated as a function of time and temperature. The synthesis by this method proceeds in two steps. The rapid formation of a predominantly amorphous disordered mesoporous aluminosilicate precursor phase is followed by the formation of globular highly mesoporous zeolite particles involving dissolution of the precursor phase. It is difficult to completely convert the initial phase into the final hierarchical zeolite. This limits the amount of aluminium built into the MFI network and the resulting Brønsted acidity. In the presence of iron, more crystalline hierarchical zeolite is obtained. These Fe-containing zeolites are excellent catalysts for the selective oxidation of benzene to phenol. Their hierarchical pore structure leads to higher reaction rates due to increased mass transfer and increased catalyst longevity despite more substantial coke formation.

Preparation of high energy fuel JP-10 by acidity-adjustable chloroaluminate ionic liquid catalyst

The isomerization of endo-tetrahydrodicyclopentadiene (endo-THDCPD) to its exo-isomer (JP-10) has been investigated by using chloroaluminate ionic liquids (ILs) as catalysts. The catalyst activity and selectivity could be optimized by varying the mole fraction of AlCl3 in the IL. Undesirable by-products derived from side-reactions such as skeletal rearrangement, alkylation, cracking, and dimerization could be minimized by appropriate catalyst design and adjustment of the reaction conditions. The catalyst system was further optimized by selecting 1-butyl-3-methylimidazolium chloride as the basic IL and adding 0.60–0.65 mole fraction of AlCl3 as the promoter. Using the optimized catalyst system, the isomerization of endo-THDCPD to exo-THDCPD proceeded at a fast rate at 50°C with 98.9% conversion and 100% selectivity. The catalyst longevity has been demonstrated by recycling the IL several times without a noticeable reduction in catalytic activity.

ChemInform Abstract: Ruthenium Carbene-Based Olefin Metathesis Initiators: Catalyst Decomposition and Longevity.

Thermolytic decomposition pathways were studied for several ruthenium carbene-based olefin metathesis catalysts. Substituted carbenes were found to decompose through bimolecular pathways while the unsubstituted carbene was found to decomposed unimolecularly. Implications for ring-closing metathesis are discussed, and the longevity of several ruthenium-based catalysts are compared.

Long-Term Performance of Pt-Decorated Carbon Nanotube Cathodes in Phosphoric Acid Fuel Cells

We report the electrochemical properties and performance of Pt-decorated carbon nanotube (Pt-CNT) catalysts for long-term operation in phosphoric acid fuel cells (PAFCs). Electrochemical measurements of Pt-CNT catalysts including cyclic voltammetry, rotating ring disk electrode voltammetry, and electrochemical impedance spectroscopy were conducted to evaluate the catalyzed oxygen reduction reaction (ORR). Furthermore, we tested the long-term performance of the Pt-CNT catalysts in 2′′ × 2′′ PAFC cathodes operating at 190 °C in 85% H3PO4 for extended periods (up to 240 days). Lifetime studies show that electrodes containing the Pt-CNT catalysts were approximately 20 times more stable than conventional Pt-C catalyst materials, even with a substantially thinner catalyst layer. This finding of the enhanced Pt-CNT catalyst stability bodes well for possible personal electronics or automotive applications, where catalyst longevity is an essential requirement.

A Phenomenological Study on the Synergistic Role of Precious Metals in the Steam Reforming of Logistic Fuels on Trimetal-Supported Catalysts

Fuel processors are required to convert sulfur-laden logistic fuels (jet fuels, diesel, and coal) into fuel cell quality hydrogen-rich reformate with little or no sulfur for extended periods. Sulfur poisons and deactivates the reforming catalyst, therefore, sulfur-tolerant catalysts ought to be developed. In this paper, the development, characterization, and evaluation of a series of nanoscale ceria-supported reforming catalysts containing three noble metals in low concentration (1 wt% ≤ total metal loading ≤ 1.33 wt%) for the steam-reforming of kerosene (a JP-8 surrogate) are reported. Their performance is quantified in terms of H2yield, tolerance towards sulfur in the fuel, and the on-stream stability and compared with that of monometal and bimetal analogs under identical conditions. Due to the inherent cooperative synergy, a trimetal catalyst was found far superior to its mono- and bimetallic analog containing same amount of the precious metal loading in terms of quality of the reformate (measured by H2level in steady-state) as well as the catalyst longevity on-stream prior to deactivation. At the same time a mechanistic correlation between the distinct role of a given precious metal and the extent of its loading in each of the formulations and quality of the corresponding desulfurized H2-rich reformate was discovered.

Effect of mesoporosity against the deactivation of MFI zeolite catalyst during the methanol-to-hydrocarbon conversion process

The effects of mesoporosity on catalyst longevity of methanol-to-hydrocarbon (MTH) reactions have been investigated using a number of MFI zeolites with different degrees of mesoporosity, which were obtained via the post-synthetic desilication, dry-gel conversion in nanocarbon templates, and hydrothermal synthesis with the addition of organosilane surfactants. The MTH catalytic lifetime could be increased by more than three times due to the generation of mesopores. The cause for catalyst longevity was investigated by probing the location of coke that formed during the reaction using argon adsorption measurements. The result showed that the coke formed mainly on mesopore walls in the case of mesoporous zeolite. On the other hand, the coke was more heavily deposited inside micropores in the case of solely microporous zeolites. The short diffusion path lengths and hence facile diffusion of coke precursors were most likely the cause of the improvement in the catalytic lifetime.

A comparison of mixed-conducting oxygen-permeable membranes for CO 2 reforming

SrFeCo 0.5O x (SFC) and Ba 0.5Sr 0.5Co 0.8Fe 0.2O x (BSCF) ceramic membranes have been evaluated for the CO 2 reforming of CH 4 at 800 °C over a Pt/ZrO 2 and a Pt/CeZrO 2 (17.5 wt% Ce) catalyst. The SCF membrane was a dense membrane approximately 2 mm thick while the BSCF membrane had a 400 μm dense layer supported on a 2.2 mm porous BSCF layer. Both membranes exhibited good mechanical integrity and stability under reaction conditions, and the membrane effect on methane conversion was roughly proportional to the apparent oxygen production of the membranes. Methane conversion and water production increase simultaneously in the presence of the membrane and the membranes improve catalyst longevity as well as activity. Results suggest that membrane oxygen reacts with hydrogen at the membrane surface to form water that can then participate in the reaction set via steam reforming. Among the combinations of membrane and catalyst tested, the Pt/CeZrO 2 catalyst on the BSCF membrane produced the highest methane conversion and H 2:CO ratios as well as the most water. This test also yielded the greatest net membrane oxygen production, with more than three times the oxygen production of the BSCF test with the Pt/ZrO 2 catalyst. The SFC membranes exhibited steady state net oxygen production of zero or less. Negative membrane oxygen production values are attributed to the reduction of CO 2 to CO on the membrane surface with incorporation of the oxygen into the membrane material.

Simultaneous Coke Reduction with Improved Syngas Production during Propane Steam Reforming using Forced CO2 Cycling

Carbon deposition during hydrocarbon steam reforming is often a major cause of pathological reactor performance and catalyst deactivation. In this paper, we report the effect of forced periodic cycling between propane-steam reforming feed and a carbon gasifying agent (CO2) as a novel reactor strategy to both improve product yield (H2 and CO) and catalyst longevity. Experiments were carried out over Co-Ni/Al2O3 catalyst in a fluidized bed reactor. Cycle period, ?, was varied between 5 to 20 mins at 5 different cycle splits, (0.1 ? s ? 0.9). Both H2 and CO formation rates were higher (up to 5-fold and more than 10-fold, respectively) than that attainable under steady-state operation at all periods investigated. In particular, the time-average H2:CO ratio was lower (< 3.0) than the steady-state equivalent for the pure propane steam reforming (14.0), although it increased monotonically with cycle split. Composition cycling with CO2 also improved catalyst stability and longevity compared to steady-state performance at the cycle periods examined. This strategic reactor operation is therefore a potentially useful key to green process engineering in the overall petrochemical plant design to effect greenhouse gas emission reduction.

Catalytic reduction of N-nitrosodimethylamine with nanophase nickel–boron

Recent work by the authors shows that toxic N-nitrosamines, widely detected in disinfected wastewater and drinking water and recalcitrant towards conventional treatment processes, can be rapidly reduced to less hazardous products by treatment with hydrogen and Raney nickel catalysts. Unfortunately, Raney Ni catalysts are pyrophoric when dry and are readily deactivated when exposed to air, severely limiting their application for water treatment. In this work, a non-pyrophoric and air-tolerant nickel–boron (NiB) catalyst is described, and its reactivity with N-nitrosodimethylamine (NDMA) is quantified. The catalyst, prepared by aqueous reduction of NiCl2 with NaBH4, has an elemental composition of 85wt.% Ni and 7wt.% B. Nanophase primary catalyst particles are formed and aggregate in micrometer-sized assemblies in solution. The catalyst has a specific surface area of 18m2g−1, and the surface contains Ni(0) and B in a mixture of oxidation states (0/+III). Kinetic studies show that NDMA is rapidly reduced via hydrogenation to dimethylamine and ammonia in H2(g)-saturated (PH2=1 atm) aqueous NiB suspensions, with mass- and surface area-normalized first-order rate constants of 29.5±2.4LgNi−1h−1 and 1.38±0.11Lmcat−2h−1, respectively. Although the mass-normalized rate constant is less than that measured for Raney Ni, the surface area-normalized rate constant is greater, suggesting higher intrinsic reactivity of the NiB surface if the availability of surface sites for NDMA reactions on either catalyst surface is not significantly affected by aggregation of the catalyst nanoparticles. Kinetic studies show that reactivity of the NiB catalyst with NDMA is unaffected by solution pH and extended pre-exposure of the dry catalyst to air (Raney Ni is immediately deactivated by exposure to air). The NiB catalyst is also more tolerant of dissolved oxygen and low concentrations of dissolved (bi)sulfide than Raney Ni, suggesting potential for greater catalyst longevity during water treatment applications.

Palladium-Catalyzed Formylation of Aryl Bromides: Elucidation of the Catalytic Cycle of an Industrially Applied Coupling Reaction

The first comprehensive study of the catalytic cycle of the palladium-catalyzed formylation of aryl bromides with synthesis gas (CO/H2, 1:1) is presented. The formylation in the presence of efficient (Pd/PR2(n)Bu, R = 1-Ad, (t)Bu) and nonefficient (Pd/P(t)Bu3) catalysts was investigated. The main organometallic complexes involved in the catalytic cycle were synthesized and characterized, and their solution chemistry was studied in detail. Comparison of stoichiometric and catalytic reactions using P(1-Ad)2(n)Bu, the most efficient ligand known for the formylation of aryl halides, led to two pivotal results: (1) The corresponding carbonylpalladium(0) complex [Pd(n)(CO)(m)L(n)] and the respective hydrobromide complex [Pd(Br)(H)L2] are resting states of the active catalyst, and they are not directly involved in the catalytic cycle. These complexes maintain the concentration of most active [PdL] species at a low level throughout the reaction, making oxidative addition the rate-determining step, and provide high catalyst longevity. (2) The product-forming step proceeds via base-mediated hydrogenolysis of the corresponding acyl complex, e.g., [Pd(Br)(p-CF3C6H4CO){P(1-Ad)2(n)Bu}]2 (8), under mild conditions (25-50 degrees C, 5 bar). Stoichiometric studies using the less efficient Pd/P(t)Bu3 catalyst resulted in the isolation and characterization of the first stable three-coordinated neutral acylpalladium complex, [Pd(Br)(p-CF3C6H4CO)(P(t)Bu3)] (10). Hydrogenolysis of 10 needed significantly more drastic conditions compared to that of dimeric 8. In the presence of amine base, complex 10 gave a catalytically inactive diamino acyl complex, which explains the low activity of the Pd/P(t)Bu3 catalyst formylation of aryl bromides.

Ultra‐Low Catalyst Loading as a Concept in Economical and Sustainable Modern Chemistry: The Contribution of Ferrocenylpolyphosphane Ligands

AbstractThe challenge of sustainability in modern chemistry will be met with new technologies and processes provided significant progress is made in several key research areas, such as the expansion of chemistry from renewable feedstock, the design of environmentally benign chemicals and solvents, the minimization of depletive resources, and the development of high‐performance catalysis. In this prospect, ligand chemistry is a pivotal science that links modern‐organic,‐inorganic, ‐organometallic, and ‐coordination chemistry through a vast number of valuable applications, precisely associated to catalysis. We review in this article our recent work on catalysis promoted by original ferrocenyl tetra‐, tri‐, and diphosphane ligands. New concepts, taking advantages of this family of branched multidentate ligands, have led to progress in homogeneous catalysis. The search for catalyst longevity and ultra‐low catalyst loadings (high turnover numbers), on the basis of multidentarity effects and robustness of the ferrocenyl backbone were focused on high‐value palladium‐catalyzed C–C cross‐couplings, such as Heck, Suzuki, and Sonogashira reactions. Low catalyst loading was also explored for C–N cross‐coupling in the allylic amination of achiral substrates. The advantages of this newly born family of ligands in the class of multidentate compounds are discussed in light of the valuable information gathered up to now on their reactivity, structure, and mechanistic behavior.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

New concepts in multidentate ligand chemistry: effects of multidentarity on catalytic and spectroscopic properties of ferrocenyl polyphosphines

This tutorial review devoted to ligand chemistry deals with the design and properties of ferrocenyl polyphosphines, an original class of multidentate ligands. The development of a varied library of ferrocenyl tetra-, tri- and diphosphine ligands is reviewed. The multidentate nature of these species has led to unique spectroscopic and catalytic properties, in which the spatial proximity of phosphorus atoms is crucial. Regarding their catalytic applications, the key issues of catalyst longevity and ultralow catalyst loadings are discussed. Another part is concerned with fundamental advances gained in physical chemistry for structure elucidation by the study of the intriguing "through-space" NMR spin-spin J couplings existing within several of these polyphosphines.

Exploiting Noninnocent (E,E)‐Dibenzylideneacetone (dba) Effects in Palladium(0)‐Mediated Cross‐Coupling Reactions: Modulation of the Electronic Properties of dba Affects Catalyst Activity and Stability in Ligand and Ligand‐Free Reaction Systems

The reactivity of palladium(0) complexes, [Pd(0) (2)(dba-n,n'-Z)(3)] (n,n'-Z=4,4'-F; 4,4'-CF(3); 4,4'-H; 4,4'-MeO) and [Pd(0)(dba-n,n'-Z)(2)] (n,n'-Z=4,4'-CF(3); 4,4'-H; 3,3',5,5'-OMe), used as precursor catalysts with suitable donor ligands (e.g. phosphines, N-heterocyclic carbenes), has been correlated in several palladium(0)-mediated cross-coupling processes. Increasing the electron density on the aryl moiety of the dba-n,n'-Z ligand increases the overall catalytic activity in the majority of these processes. This effect primarily derives from destabilization of the L(n)Pd(0)-eta(2)-dba interaction (in dpi-pi* synergic bonding, n=1 or 2), which ultimately increases the global concentration of catalytically active L(n)Pd(0) available for reaction with aryl halide in the first committed step in the general catalytic cycle(s) (oxidative addition). Decreasing electron density on the aryl moiety of the dba-n,n'-Z ligand stabilizes the Pd(0)-eta(2)-dba interaction, reducing catalytic activity. The specific type of dba-n,n'-Z ligand appears to also play a stabilizing role in the catalytic cycle, preventing Pd agglomeration, and increasing catalyst longevity. A subtle balance therefore exists between the L(n)Pd(0) concentration (and the associated catalytic activity) and catalyst longevity. Changing the type of dba-n,n'-Z ligand controls the concentration of L(n)Pd(0) and the rate of the oxidative addition step, and not other intimate steps within the catalytic cycle(s), for example, transmetallation (or carbopalladation) and reductive elimination. The role of dba-n,n'-Z ligands in Heck arylation is more convoluted and dependent on the alkene substrate employed, although trends have emerged. Changes in the structure of dba-n,n'-Z had a minimal affect on Buchwald-Hartwig aryl amination processes. A secondary Michael reaction of dba-n,n'-Z with amine and/or base effectively lessens its interference in the catalytic cycle.

Cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane: Tedicyp, an Efficient Ligand in Palladium-Catalysed Reactions

A tetraphosphine, the cis,cis,cis-1,2,3,4-tetrakis(diphen­ylphosphinomethyl)cyclopentane (Tedicyp), has been synthesised and used in Pd catalysis. This tetraphosphine in combination with [(η3-C3H5)PdCl]2 affords a catalyst precursor which is amongst the most active in allylic substitution, Heck, Suzuki or Sonogashira-type reactions. Turnover numbers up to 980,000 for allylic amination, 9,800,000 for allylic alkylation, 97,000,000 for Suzuki cross-coupling, 2,800,000 for Sonogashira alkynylation and 210,000,000 for Heck reaction have been obtained with this catalyst precursor. This complex seems to be very stable. This stability probably comes from the presence of the four diphenylphosphinoalkyl groups stereospecifically bound to the same face of the cyclopentane ring, which probably increases the coordination of the ligand to the metal and therefore, the catalyst longevity. Ligands are also often needed in order to modulate the rate of some of the catalytic steps like oxidative addition or reductive elimination. The ‘pressure to coordinate’ resulting of the presence of these four phosphines in a half space might also accelerate the reductive elimination step in the catalytic cycles. The complex formed by association of Tedicyp and [(η3-C3H5)PdCl]2 seems to possess a fine balance of steric and electronic properties, which allow fast catalytic processes with a very wide variety of substrates.

Process limitations in a whole-cell catalysed oxidation: Sensitivity analysis

Biocatalytic oxidation processes have to date presented major problems for scale-up, in part due to the complexity of the number of process variables. In this paper we have analysed the key limitations in such processes using the Baeyer–Villiger monooxygenase catalysed synthesis of optically pure lactones as an illustrative example. Limitations in product concentration, catalyst longevity and reaction rate were quantified and their effect on previously defined process metrics identified. Of particular interest is the way these metrics change with catalyst concentration. Using this assessment, the sensitivity of the metrics to potential changes to process and catalyst were analysed. We believe such an analysis is of general use to guide development efforts for a given biocatalytic reaction.