effect of carbon and mgal oxide supports and potassium promoter on higher alcohol selectivity over...

Effect of Carbon and MgAl Oxide Supports and Potassium Promoter on Higher Alcohol Selectivity over MoS 2 Catalysts during Induction Period Jin Wai Goh, Micaela Taborga Claure, Christopher W. Jones Georgia Institute of Technology Background Selectivity Results Conclusions Effect of Support and Promoter on Selectivity Catalyst Preparation Lower Olefins (C2-C4) are the key building blocks in the chemical industry • Primarily produced by steam cracking • Ethylene is the largest volume petrochemical produced worldwide • Growing demand for olefins-doubled over the past 15 years 1 • Alternative energy sources to olefins needed Syngas-based processes to olefins include Higher alcohol (C2-C4) from syngas • Most widely studied family-noble metal catalyst is Rh • Modified methanol or modified Fisher-Tropsch catalysts • Modified MoS 2 based catalysts with K Previous work • K shifts product distribution from hydrocarbons to higher alcohols 2,3,4,5 • K/MoS 2 on carbon (C) supports are selective towards hydrocarbons 6 • K/MoS 2 on mixed MgAl oxide (MMO) supports yield high C 2+ OH selectivity 2,6,7 • K/MoS 2 domain was correlated with selectivity (single layes~HC selectivity, double layers~ C 3+ OH selectivity) 6 Further understand the effect of support and promoter on structure-selectivity relationship. Objective Supported Catalysts CO hydrogenation reactions with syngas High pressure (1500 psig) Medium temperature (310 °C) (in-situ sulfidation at 450 °C) Composition All Catalysts Mo 5 wt. % Promoted Catalysts K 3 wt. % Mo/K (mol) = 1 • Unsupported MoS 2 produced primarily C 1 species while supported MoS 2 produced primarily C 2+ species. • K promotion increases the induction period because K intercalation requires a ‘break-in’ period. 5 • Weak Mo-C interactions created single layers on the carbon support – selective towards hydrocarbons. • Strong Mo-MMO interactions created double layer formation on the MMO support – selective towards higher alcohols (only for K/MoS 2 ). Future Work • Investigating absorbed species with in-situ IR • Investigate the structure of the catalyst via in-situ Raman and in-situ XAS References 1 H.M. Torres Galvis, K.P. de Jong, ACS Catal. 3 (2013) 2130. 2 M.R. Morrill, N.T. Thao, Catal Lett. 142 (2012) 875 3 A. Andersen, S.M. Kathmann, J. Phys. Chem. 116 (2012) 1826 4 V.S. Dorokhov, D.I. Ishutenko, Kin & Catal 54 (2013) 24 5 V.P. Santos, B. Linden, ACS Catal. 3 (2013) 1634 6 M.T.Claure, S.H. Chai, J. Catal. 324 (2015) 88 7 M.R. Morrill, N.T. Thao, ACS Catal. 3 (2013) 1665 Unsupported Catalysts Mo C MMO K Unpromoted Promoted MoS 2 Domains Unpromoted Promoted • Selective towards hydrocarbons • Selective towards methane Unpromoted Promoted • Selective towards MeOH, followed by EtOH • Selective towards C 2+ OH • Selective towards hydrocarbons • Low higher alcohol selectivity • Selective towards ethane Predominantly single layer 6 Predominantly double layers 6 Multilayers 7 Hypothesized MoS 2 domain Hypothesized MoS 2 domain Hypothesized MoS 2 domain C Mo MoC MoKC MoMMO MMO MoC MoKC bulk MoS 2 MoMMO MoKMMO MoKMMO K/ bulk MoS 2 MoC Mo MoKC MoMMO MoKMMO Bulk MoS 2 K/Bulk MoS 2 Bulk MoS 2 K/Bulk MoS 2 MoS 2 C MoS 2 MoS 2 C MoS 2 MMO MoS 2 MoS 2 MMO MoS 2 MoS 2 K + MoS 2 MoS 2 MoS 2 MoS 2 MoS 2 MoS 2 MoS 2 MoS 2 K +

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Page 1: Effect of Carbon and MgAl Oxide Supports and Potassium Promoter on Higher Alcohol Selectivity over MoS2 Catalysts during Induction Period

Effect of Carbon and MgAl Oxide Supports and Potassium Promoter on Higher Alcohol Selectivity over MoS2 Catalysts during Induction Period

Jin Wai Goh, Micaela Taborga Claure, Christopher W. JonesGeorgia Institute of Technology

Background Selectivity Results

Conclusions

Effect of Support and Promoter on Selectivity

Catalyst Preparation

Lower Olefins (C2-C4) are the key building blocks in the chemical industry• Primarily produced by steam cracking• Ethylene is the largest volume petrochemical produced worldwide• Growing demand for olefins-doubled over the past 15 years1

• Alternative energy sources to olefins needed

Syngas-based processes to olefins include

Higher alcohol (C2-C4) from syngas• Most widely studied family-noble metal catalyst is Rh• Modified methanol or modified Fisher-Tropsch catalysts• Modified MoS2 based catalysts with K

Previous work• K shifts product distribution from hydrocarbons to higher alcohols2,3,4,5

• K/MoS2 on carbon (C) supports are selective towards hydrocarbons6

• K/MoS2 on mixed MgAl oxide (MMO) supports yield high C2+OH selectivity2,6,7 • K/MoS2 domain was correlated with selectivity (single layes~HC selectivity,

double layers~ C3+OH selectivity)6

Further understand the effect of support and promoter on structure-selectivity relationship.

Objective

Supported Catalysts

CO hydrogenation reactions with syngasHigh pressure (1500 psig)Medium temperature (310 °C)(in-situ sulfidation at 450 °C)

CompositionAll CatalystsMo 5 wt. %Promoted CatalystsK 3 wt. %Mo/K (mol) = 1

• Unsupported MoS2 produced primarily C1 species while supported MoS2 produced primarily C2+ species.

• K promotion increases the induction period because K intercalation requires a ‘break-in’ period.5

• Weak Mo-C interactions created single layers on the carbon support – selective towards hydrocarbons.

• Strong Mo-MMO interactions created double layer formation on the MMO support – selective towards higher alcohols

(only for K/MoS2).

Future Work• Investigating absorbed species with in-situ IR• Investigate the structure of the catalyst via in-situ Raman

and in-situ XAS

References1H.M. Torres Galvis, K.P. de Jong, ACS Catal. 3 (2013) 2130.2M.R. Morrill, N.T. Thao, Catal Lett. 142 (2012) 8753A. Andersen, S.M. Kathmann, J. Phys. Chem. 116 (2012) 18264V.S. Dorokhov, D.I. Ishutenko, Kin & Catal 54 (2013) 245V.P. Santos, B. Linden, ACS Catal. 3 (2013) 16346M.T.Claure, S.H. Chai, J. Catal. 324 (2015) 887M.R. Morrill, N.T. Thao, ACS Catal. 3 (2013) 1665

Unsupported Catalysts MoC

MMO

Unpromoted Promoted

MoS2 Domains

Unpromoted Promoted

• Selective towards hydrocarbons

• Selective towards methane

Unpromoted Promoted

• Selective towards MeOH, followed by EtOH

• Selective towards C2+OH

• Selective towards hydrocarbons• Low higher alcohol selectivity

• Selective towards ethane