mefco final dissemination event€¦ · distribution of basic sites - alkali earth metals i.e. ca,...

MefCO2 Final dissemination event

Catalyst and process engineering

Matej Huš, Kemijski inštitut

James Hayward, Cardiff Catalysis Institute

28th May, 2019

MefCO2 – Methanol fuel from CO2

Methanol synthesis-commercial/emerging technologies

Feedstock: fossil fuel based vs carbon dioxide based

More than 40 million metric tons produced annually

Syngas sources:

• Natural gas steam reforming (≈75 %)

• Coal gasification (≈ 10 %)

• Mainly CO and H2

Or:

• Waste CO2+H2 produced at electricity peaks

• Mainly CO2 and H2→Modification of catalyst

History

• Before 1923-dry distillation of wood

• 1923-1966 Mittasch high pressure process

• 1966-present ICI low pressure process


Methanol synthesis-commercial technologies

Reactor types*

Process conditions: 200-300 °C, 50-100 bar

Features

• Suited for large scale operation (up to million ton per year)

• Conditions suited for fast reaction in compromise with equilibrium

• Utilization of reaction heat

Disadvantages

• Not responsive to varying load

• Not economic out of design conditions

*G. Bozzano, F. Manenti, Efficient methanol synthesis: Perspectives, technologies and optimization strategies, Progress in energy and Combustion Science 56 (2016) 71-105


Aims of the Research

Improving upon existing catalyst systems

Initial Catalyst Modifying the Catalyst Applying Understanding

• Based on ICI catalyst developed in the 1960s

• Catalyst consists of a mixture of copper, zinc, and alumina

• Copper is the active phase

• Materials prepared by co-precipitation

• Precursor phase is malachite

• Changes in metal ratios:

• Altering the relative amounts of copper, zinc and alumina

• Changes in substrates

• Substitution of the zinc for different elements

• Ce, Zr, Mg, Ga, Al, In, Mn, Ti, Si

• Changes in dopants

• Substitution of the alumina for different elements

• B, Ga, In, Mg, Sn, Ce, Zr

• Catalysts screened in multi-bed reactor

• Wide range of characterisation techniques used

• What trends can we observe?

• Can we use these trends in catalyst design?


Initial Results

Modifications of the malachite precursors

Screening conditions: 200 – 300 °C, 20 bar pressure, 1:3 CO2:H2 gas mix

• Increased copper loading does not always increase activity

• Increased surface area of overall material a factor

• Malachite phase important, but mostly because of effect on copper specific surface area

• Dominant trend: Increase in copper specific surface area increases yield

• What approaches can we take to improve copper SSA?


Improving on Malachite

Alternative preparation methods and precursor phases

Magnesium substitution and Supercritical Antisolvent (SAS) Precipitation

Partial substitution of Zn byMg can lower Cu particle size

Complete substitution lesseffective; some zinc needed

SAS process produces higherCu surface areas

Time and resource intensive

Catalyst Cu SSA (m2/g)

SAS 1 32

SAS 2 33

SAS 3 31

SAS 4 34

Mg % Cu SSA (m2/g)

0 31

10 36

20 35

30 33


Improving on Malachite

Treated hydrotalcite precursors

Hydrotalcite structure: Treatment Effects: Testing Data:

Reported in literature to havesmaller copper nanoparticles

Aggregation of layers reducessurface area

Solvent treatment to preventaggregation?

Increased activity vs. industrialstandard

Studies into stability and scale-upneeded

Potential new precursor?

Standard Untreated Treated

Surface

Area

75-90 21 339

Cu Surf.

Area

28 7 55


Catalyst screening reactor

5 parallel reactors

• More than 60 catalysts tested

• Almost 24/7 operation

• User friendly

• 20-400 °C

• 10-250 sccm

• 10-85 bar, with modification up to 100 bar

• Versatility

• Recycle reactors are rare on laboratory scale, commercially not available

Mass flow controllers

Heated sampling system

Micro gas chromatograph

Reactor with catalyst cartridge

Gas recycle


Catalyst screening - experimental

Procedure

Distribution of basic sites - Alkali earth metals i.e. Ca, Mg, Sr and Ba Copper metallic phase – Calcination temperature, Ultrasonic, Hydrothermal Solution combustion and Solid state methods

Catalyst Material Metal

Alkaline earth metal catalysts

Cu-Alkali earth metal-Alumina

Ca, Mg, Sr and Ba

Best alkali metal proceeded to the second step

Transition metal catalystsTranition metal- alkali

metal-AluminaNi,Mn, Fe and Co

Best catalyst from this stage proceeded to the third step

Effect of supports TM-ALKM-supports Al, Si, Ti, Ce and Zr

Best catalyst from this stage proceeded to the fourth step

Promoted catalystPromoter-(Good catalyst and Bad catalysts from three stages)

Na, K, Cs, Cr, V and Mo


Catalyst screening - experimental

Effect of Cu+/Cu0 ratioCatalyst activity at T = 250 °C and P = 20 bar

Time on-line analysis over Zn and Mg based catalysts (CO2:H2 = 1:3, GHSV = 6000 h-1, P = 20 bar)


Process modelling

DFT (first-principles)

Cu-based: Zn, Cr, Fe and Mg inverse catalysts tested

Detailed structures of all possible intermediates


Process modelling

DFT (first-principles)

Mechanism

Rationale: To optimise the process for non-ideal conditions (impurities, different T, pressure, CO2 feed)


Process modelling

Mesoscale (catalytic surface)

Kinetic Monte Carlo simulations


Process modelling

Mesoscale (catalytic surface)

Mean-field microkinetics Selectivity at laboratory conditions for four different catalysts


Process modelling

Micro-kinetics coupled with CFD

Pressure drop and packing

hp

dDS


Process modelling

CFD simulations with micro-kinetic model

Parameter Value Unit

ρs 1770 [kg m−3]

dp 5.47×10−3 [m]

cps 5.0 [kJ kg−1

K−1]

λc 0.004 [W m−1

K−1]

av 626.98 [m2 m−3]

es/ 0.123 [–]

Tube length 7.022 [m]

Layer

Thickness

8×10−7 [m]

Tube diameter 0.038 [m]

Shell diameter 0.053 [m]

Over 15000

pellets

Lurgi catalyst specifications

Packing in a single tube


Take-home message

Patents, publications and presentations

• Extensive and systematic experimental testing of prospective catalysts

• More than 60 catalysts synthesised and tested + industrial ones (e.g. Lurgi)

• CO2 hydrogenation to methanol is a mature process. However, niche catalysts were synthesised and tested for non-optimal conditions.

• Most important effects determining the performance: Cu+/Cu0 ratio, secondary metal, support, dispersion, method of preparation

• Multiscale modelling:

• First-principles calculations show the reaction mechanism

• Meso-scale simulations show the temporal evolution of the catalytic surface

• Coupling with CFD necessary to describe the process on a macroscopic level

• Results of high scientific importance:

• Huš M. et al. ACS Catalysis 2019, 9 (1), 105-116

• Dasireddy V. D. B. C. et al. Renewable energy 2019, 140, 452-460.

• Dasireddy V. D. B. C. et al. Fuel, 2018, 233, 103-112.

• Dasireddy V. D. B. C. et al. Journal of CO2 utilization, 2018, 28, 189-199.

• Pavlišič A. et al. Powder technology, 2018, 323, 130-139.

• Huš M. et al. Applied Catalysis B: Environmental 2017, 207, 267-278.

• Huš M. et al. Catalysis Science & Technology 2017, 7 (24), 5900-5913.

• Kopač D. et al. The Journal of Physical Chemistry C, 2017, 121 (33), 17941-17949.

• Hayward J. S. et al. ChemCatChem, 2017, 9 (9), 1655-1662.

• The effects of partial magnesium substitution on green methanol catalysts, submitted

• Delaminated hydrotalcites as precursors for green methanol catalysts, submitted

Conference contributions:

• UK Catalysis Conference

• Faraday Discussion

• Cardiff Catalysis Conference

• AIChE,

• North American Symposium on Chemical Reaction Engineering

Patent applications:

• Patent Pending GB1701382.2 – Catalyst suitable for methanol synthesis

This project has received funding from the European Union’s Horizon

2020 research and innovation programme under grant agreement

No 637016.

Thank you

mefco final dissemination event€¦ · distribution of basic sites - alkali earth metals i.e. ca,...

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