The physical hub in the RCaH has been crucial to the success of the whole Hub project. It has provided first class facilities for research in catalytic science, which are a resource for the whole community. The laboratories have been used effectively by visiting scientists and the Hub team at Harwell including those undertaking experimental work on the central facilities, while promoting fruitful interactions other groups in the RCAH and the Harwell campus more broadly.
Custom catalysis labs
The UK Catalysis Hub has developed custom catalysis labs and analysis at the RCAH including a gas handling laboratory and provided the bespoke catalysis instrumentation (EPSRC Grant EP/K005030/1). The ring-main system has eight lines for different specialty gases, with each gas having ten individually regulated drop-off points around the laboratory.
The catalysis equipment currently available includes:(i) rapid scanning FT-IR with combined XAFS/ DRIFTS capabilities with Custom designed Portable gas handling system, (ii) a suite of autoclave reactors, (iii) a multi-tubular reactor assembly for heterogeneous catalysis studies, (iv) a flow reactor for homogeneous catalysis, (v) a Hiden CATlab for heterogeneous catalysis studies, TPO, TPD and TPR, (vi) a suite of high performance liquid and gas chromatographs and (vii) a microwave-plasma atomic emission spectrometer, (viii) Quantocrome four station BET surface area analyser and vii) Quantchrom ChemBET TPO/TPD analyster.
image credit: UK Catalysis Hub
In addition to the gas handling lab the Catalysis team also occupy a lab for preparative chemistry work, which has also been aided by the transfer of the necessary equipment for preparing and handling air and moisture sensitive compounds (Schlenk line, vacuum pumps etc.). The catalysis team currently has office space sufficient for 20 desks and 158 m2 of laboratory space.
a. DRIFTS Setup image credit: UK Catalysis Hub
Diffuse Reflectance Infrared Fourier Transform Spectroscopy is an infrared technique ideal for research on catalyst surfaces. It allows the chemical and structural evaluation of all types of solid surfaces (including non-transparent, highly absorbing materials, coatings and roughened surfaces).
An infrared beam focused onto a fine particulate material can interact with it in several possible ways. It can be absorbed, reflected from the surface or penetrate the particles before being scattered. Diffuse reflectance results from the penetration of the incident radiation into one or more particles and subsequent scattering from the sample matrix.
The advantages of DRIFTS over conventional FTIR methods include the following: (i) DRIFTS is fast and non-destructive since the sample can be analysed as is or in powdered form, (ii) It is well suited to the analysis of strongly absorbing materials which are characterized by very low signals and sloping baselines when investigated in transmission mode, (iii) It requires little or no sample preparation.
image credit: UK Catalysis Hub
Our Drifts setup consists of an Agilent Cary 680 FTIR spectrometer with an MCT detector, gas delivery system, a Harrick reaction chamber with high pressure dome, a Praying Mantis Diffuse Reflection Accessory and a Hiden Analytical mass spectrometer. The sample is filled (either pure or mixed with an IR transparent matrix (e.g. KBr)) in a sample cup and placed inside the reaction chamber. The IR beam is directed into it by the Praying Mantis accessory, a highly efficient diffuse collection system which minimizes the detection of the specular component. The IR radiation interacts and is reflected off the surfaces of the particles, resulting in the light being diffused or scattered as it moves through the sample. This scattered energy is directed to the detector in the spectrometer by the output mirror. The altered IR beam is recorded by the detector as an interferogram, which is then used to generate a spectrum.
Specifications
The specifications listed below are the limits of the instrumentation. These are dependent on several factors including gases used, type of windows and O-rings and conditions such as vacuum.
• Temperature: RT – 910°C
• Pressure: 10-6 Torr – 34 bar
• Gases available: He, N2, Ar, H2, 10% O2, 10% CO, 10% CH4, 10% NH3
• Organic liquid injection using heated lines
b. The da Vinci arm
The da Vinci arm is a unique articulated opto-mechanical accessory designed for analysing samples outside the sample compartment. The sampling head is configurable for diffuse and specular reflectance. It facilitates a small sampling spot size, which allows analysis with high spatial resolution.
The optics involved in the working of the da Vinci arm is as follows: the optics in the sample compartment directs the IR beam through the arm to the sampling spot which is some sample, the light reflected back from the sample is directed towards the detector. Our Da Vinci arm is principally used for measurements with x-rays in conjunction with IR.
c. Dewar Transmission / Reflection Accessory Cell image credit: UK Catalysis Hub
The transmission cell (Harrick cell) allows for transmission-mode measurements of solid samples at between -196°C – 350°C in a controlled environment and is ideal for the investigation of catalytic and other solid-gas chemical reactions.
The cell is made from 316 stainless steel, with a Dewar incorporated into the accessory for low temperature operation. Gases can be flown through the cell and it can be used with vacuum down to 10-6 Torr. It is equipped with low voltage heaters for heating the sample.
The cell can also be reconfigured for near-normal (12°) specular reflection with a Variable Angle Reflection Accessory.
d. Gas Cell image credit: UK Catalysis Hub
This is a temperature-controlled cell which can be used for both static and flow applications. It is made of stainless steel, is thermally isolated and has a path length of 10 cm. The maximum operable temperature of the cell is defined by the o-ring material. O-rings available with us include Kalrez (Temperature limit 260°C) and viton (Temperature limit 260°C).
e. Linkam Cell image credit: UK Catalysis Hub
The Linkam Cell is designed to study catalytic reactions at high temperature and pressure. The cell works in reflectance mode. The samples are mounted on ceramic fabric filters placed inside a ceramic heating element, capable of heating samples from room temperature up to 1000°C very quickly, up to 5 bar pressure. The stage body is water cooled to keep it at safe temperature.
The cell can be used with a variety of gases, including corrosive gases. Lid windows made of several different materials can be used to adapt the cell to brightfield and Raman microscopy techniques as well.
f. Agilent MP-AES
The Agilent MP-AES 4100 is a benchtop microwave plasma atomic emission spectrometer based on a robust magnetically excited microwave plasma excitation source. It is used for simultaneous multi-analyte determination of major and minor metal. MPAES employs microwave energy to produce a plasma discharge, which eliminates the need for sourcing gases in remote locations.
Atomized sample passes through the plasma, promoting the electrons to excited state. Light emission from the electrons is directed to a wide range, low noise CCD detector, measuring the intensity of each emission line and background simultaneously while providing excellent detection limits and precision.
The instrument in the Catalysis Hub is set up to run inorganic and organic samples with general detection limits between ~100 ppb – 10%, depending on element.
Along with the MP-AES, an Anton Paar Multiwave 3000 is available for digestion of solid samples. Generally, samples are digested using Aqua Regia at temperatures and pressures up to 310°C and 115 bar.
a. Parr Flow Reactors image credit: UK Catalysis Hub
Continuous flow reactors permit easier automation of sequential and parametric changes in temperature, flow rate and time. The amount of product hence is a function of time and not the size of the reactor, thus increasing safety since only small amounts of materials are present at any given time. They also bring about improved mixing and heating, and as a result, higher selectivity. They are used in a variety of industries and applications. Their length to diameter ratio can be varied to study the effect of catalyst bed length.
The Catalysis Hub has 2 flow reactors with a gas delivery system allowing a mixture of up to 3 gases with flow rates up to 100ml/min each. Liquid feed can also be pumped in using an HPLC pump. Reactions can run at up to 600°C and 69 bar. The outlet of the reactors can be connected to either GC or GCMS for inline analysis. A liquid catch pot with chiller is also used to trap out water and low boiling point products for further analysis.
b. Parr Stirred Batch Reactors
Parr’s high pressure stirred batch reactors are microreactors designed to provide as many features of larger vessels as possible in the limited space available. They are ideal for liquid phase reactions involving expensive materials and materials with limited availability. They are also useful when hazardous materials are involved in the reaction and there is the need to limit the reactants or products to a minimum for safe waste disposal.
They can be easily converted from one size to another by simply exchanging the cylinder and corresponding fittings.
The Catalysis Hub has 3 batch reactors two 50ml and one 100ml that can be operated up to 200 bar and 350°C. A liquid sampling valve is incorporated to allow samples to be taken throughout the reaction time.
c. Catlab image credit: UK Catalysis Hub
The CATLAB system is a modular benchtop analysis system for comprehensive in-situ catalyst characterization, kinetic and thermodynamic measurements. The system is designed for both isothermal and temperature programmed studies of catalytic systems. The system consists of (i) a CATLAB microreactor module, which is a fast response, low thermal mass furnace, and (ii) a Hiden Analytical QIC-20 dynamic sampling mass spectrometer, which is a compact benchtop gas analysis system for continuous analysis of gases and processes at pressures up to atmosphere.
The CATLAB uses Gas Adsorption Chromatography to directly determine metal surface areas for metals. It also allows the determination of surface coverages as a function of temperature and calculate the resulting adsorption isotherms. It can also be used to study energetics, kinetics and reaction mechanisms of catalytic systems using temperature programmed techniques up to 1000°C.
The system has an integrated pulse valve to allow pulsed chemisorption studies, 8 flow channels with varied flows between 3 – 500 ml/min and is suitable for use with corrosive gases.
a. Gas Chromatography image credit: UK Catalysis Hub
Gas chromatography is an analytical technique applicable to gas, liquid and solid samples, thus offering the possibility to separate and quantify each component of a mixture of compounds. Typically, the sample solution is injected into the instrument, wherein it is transported into a column (separation tube) by a gas stream (carrier gas). The various components are separated inside the column. The detector measures the quantity of the components that exit the column.
While measuring a sample with an unknown concentration, a standard sample with known concentration first is injected into the instrument. The data obtained enables the identification and quantification of the components present in the sample.
b. Agilent GCMS
The Agilent 7890A GC System is a state-of-the-art gas chromatograph that provides superior performance for all applications. Its performance is defined by the use of advanced electronic pneumatic control (EPC) modules and high-performance GC oven temperature control. Each EPC unit is optimized for its intended use with a specific inlet and detector option. The GC oven temperature control of the 7890A oven allows for fast and precise temperature ramping. The overall thermal performance provides optimal chromatography including peak symmetry, retention time repeatability, and retention index accuracy. The combination of precise pneumatic and temperature control leads to extremely precise retention time reproducibility, which is the basis for all chromatographic measurement. Agilent’s proprietary Capillary Flow Technology provides reliable, leak free, in-oven capillary connections that stand up to repeated GC oven cycling over time. provide gains in productivity and data integrity for routine analyses via 2-dimensional heart cutting, detector splitting, and column back flushing. It also has advanced built-in capabilities to monitor system resources (counters, electronic logs and diagnostics).
The system at the Catalysis Hub includes MS, FID and TCD detectors to allow a wide range of analysis. Incorporated vici valves allow the system to be used for online testing combined with our flow reactors.
The Quantachrome ChemBET pulsar is an automated flow chemisorption and reactivity analyser.
The chemisorption of reactive gases such as CO, hydrogen etc. on the catalysts depends on the formation of chemical bonds between the surface atoms of the solid and the gas molecules, and the dissociation of the gas molecules. Chemisorption studies can be used to evaluate the active surface area of a catalyst, which is distinct from the total BET surface area (active plus non-active).
Temperature Programmed Reduction, or Reaction, (TPR) is simply an experiment in which the amount of reduction is monitored as a function of temperature. The temperature is raised in a linear fashion so that a suitable detection system can record a characteristic reduction profile or fingerprint of the sample being tested. If the reactive gas is oxidizing (such as one containing oxygen), one can perform Temperature Programmed Oxidation.
In an analogous manner, gases that were previously adsorbed during a chemisorption study can be desorbed by once again ramping the temperature to sufficiently high values to break the chemical bonds holding the gas molecules (or atoms) on the surface of the catalyst. This type of analysis is called Temperature Programmed Desorption (TPD).
The ChemBET Pulsar can be used to perform low-cost automated TPR, TPO, TPD analyses up to 1100°C, as well as manual or automated pulse titrations (i.e. injection and peak detection) for metal area/dispersion measurements. It also offers the capability to perform BET surface area measurements. It is compatible with H2, O2, CO, CO2, N2O, SO2, NH3, N2, Ar, Ke and He.
At low temperatures, non-reactive gases (nitrogen, argon, krypton, etc.) are physisorbed by the surface. Through gas physisorption, the total surface area of the sample can be calculated by the BET method.
The Quadrasorb EVO is a versatile high throughput gas adsorption instrument. 4 samples can be analysed simultaneously. It operates by measuring the quantity of gas adsorbed onto or desorbed from a solid surface at some equilibrium vapor pressure by the static volumetric method. To obtain the data, a known quantity of adsorptive gas is admitted or removed in and out of a sample cell containing the solid adsorbent at a constant temperature below the critical temperature of the adsorbate. As adsorption or desorption occurs the pressure in the sample cell changes until equilibrium is established. The quantity of gas adsorbed or desorbed at the equilibrium pressure is the difference between the amount of gas admitted or removed and the amount required to fill the space around the adsorbent (void space).
Microporous samples are measured with Nitrogen or argon in volume-pressure range 0.001 to slightly less than 1. Low surface area samples are measured with krypton in volume pressure range 4 × 10-5 to slightly less than 1.
The volume-pressure range can be reduced to BET surface area (single and/or multipoint), Langmuir surface area, adsorption and/or desorption isotherms, pore size and surface area distributions, micropore volume and surface area using an extensive set of built-in data reduction procedures in the associated QuadraWin software.
The setup includes a FloVac Degasser that allows preparation of up to 6 samples in a single heated zone. Needle valves allow careful control of flow rate to avoid elutriation (blowing out) of fine powders.
High pressure Xe arc lamps make excellent artificial sources to simulate sunlight. The high colour temperature of the xenon lamps (6050 to 6350 K) is a close match to the solar temperature. This results in similar spectra in the UV and VIS although the lamp has some Xe emission lines in the near IR.
Our LOT Quantum Design solar simulator is a 150W Xe light source. It includes filters to filter the Xe lamp to match various atmospheric conditions and thus match well with standard spectra. The matching is better in the UV and VIS than in the IR.
This is an intelligent potentiometric titrator and synthesis controller. Our titrator setup consists of a Metrohm 902 Titrando, a “dosino” dosing unit, a magnetic stirrer with base plate, and is controlled by a Tiamo 2.3 software interface.
This is a cost-effective reactor for gas-liquid reactions, offering the possibility to control reaction temperature and feed in gas with the same coil tube reactor.
Liquid is fed through the coil and gas is fed through a separate connection at the desired pressure from a regulated supply.
The reactor can be used in two different ways:
Pre-dissolving the gas into the liquid before the reaction
Performing the reaction in the reactor itself by feeding in the gas as it is consumed by the reaction.
BAG
Working as a collective unit at RCaH has enabled the catalysis team to gain programme access to the core XAFS beamline, B18, at Diamond Light Source (DLS), which provides the team with 24 shifts (8 days) of access per allocation period. This access route increases the efficiency of data acquisition by coordinating projects to reduce the dead time of experimental set-up and by allocating small amounts of time for proof of concept investigations before a full study starts.
We are pleased to announce a new call in 2024 for a Quasi-Elastic Neutron Scattering (QENS) BAG at ISIS. We are keen to encourage users with no experience of QENS and will provide support throughout the process.
Find out about UK Catalysis Hub Block allocation access (BAG) calls on our BAG page.
Diamond Light Source and ISIS
The work of the Catalysis Hub at DLS has been mentioned in both the Diamond news magazine (summer 2013) and Diamond Podcast (Episode 24 – Catalysis). Moreover, the base at RCaH has also enabled the catalysis group to gain programme mode access to ISIS, which provides flexible access to the many beamlines available on both target stations. Sustained access to DLS and ISIS is essential in realising the synergistic benefits of the wide ranging facilities on the RAL campus.
Future facilities
Over the next five years The Hub will provide high throughput sample environments for both in situ and ex situ XAFS analysis, reactive gas environments for Quasielastic Neutron Scattering and an in situ spatially resolved plug flow reactor for neutron diffraction of liquid phase heterogeneously catalysed reactions with combined liquid phase composition analysis. Also, we will build a plug-flow reactor to be used initially in conjunction with optical microscopy platforms such as confocal and fluorescence lifetime imaging and eventually with super-resolution techniques such as SIM, STED and STORM.
Strategic Role of Location within RCaH
image credit: UK Catalysis Hub
The RCaH is proving to be an ideal location for the Catalysis Centre for three main reasons:
Catalysis is, as noted, a multidisciplinary science and the project is already profiting from interactions with other physical sciences programmes in the RCaH (especially the imaging project). Strong interactions with life sciences projects are anticipated in the future.
The Centre is becoming a major user of synchrotron and neutron facilities and usage of laser facilities is anticipated. Our close proximity to the facilities is a major advantage in ensuring their effective exploitation.
The location and ready access to the site and the fact that for university teams it is “neutral territory” has proved to be a major advantage in establishing the centre as the physical hub for the UK national catalysis programme.
More generally the Harwell/RAL campus is an increasingly strong base for an internationally leading collaborative scientific programme.
