INSTITUTUL NAŢIONAL DE CERCETARE DEZVOLTARE PENTRU TEHNOLOGII IZOTOPICE SI MOLECULARE

Str. Donath 65-103, 400293, Cluj-Napoca, Romania

Tel: +40-264-584037; Fax: +40-264-420042

Email: itim@itim-cj.ro, web: www.itim-cj.ro

PD – PN-III-P1-1.1-PD-2016-1228 (PD 92/02.05.2018)

 

 

From nanoreactor to a high performance fixed bed reactor using hierarchical MOF based catalysts

Acronym - MOFReCAT

 

Project Coordinator: Dr. Eng. Maria Mihet

Mentor of Project Coordinator: Prof. Dr. Eng. Vasile-Mircea Cristea

 

Program PN III: Human Resources

Project type: Postdoctoral Project

 

Project Timespan: May 2018 - April 2020

 

Project Team:

Dr. Eng. Maria Mihet, Project Coordinator (CV)

Prof. Dr. Eng. Vasile-Mircea Cristea, Mentor (CV)

 

Summary of the project:

Metal-organic frameworks (MOFs) are highly versatile compounds due to their exceptionally high surface area and tunable porous structure, as well as their structural diversity. The catalytic applications of MOFs are of great interest from both scientific and technological point of view due to the diversity of catalytic functionalities which can be introduced in precise locations during synthesis or post synthetically. Methanation of CO2 by H2, is an important process due to (a) the environmental benefit, and (b) the energetic/commercial one, and an example of a catalytic application for MOFs. The confined space of MOFs may play the role of a nanoreactor in case of CO2 methanation due to the possibility (a) to activate CO2 inside the pores, and (b) to introduce metal nanoparticles inside the pores which can activate the necessary H2, while the reaction may proceed between these activated species inside the pores. However, the powder form of MOFs does not make them eligible for final applications. Therefore, the present project proposal aims at making a step further in respect to the catalytic applications of MOFs in the CO2 methanation process: from nanoreactor to an intensified packed bed reactor. This intensified packed bed reactor may be obtained by shaping of MOFs through immobilization on various structures, with important advantages: (a) diffusion limitations may be avoided inside the packed bed, (b) pressure drop along the packed bed can be minimized; (c) catalyst attrition and leaching is limited under operation (recovery and reuse); (d) the catalytic active material can be used more effectively; (e) mechanical stability may be enhanced. The main objective of the present project proposal is to shape MOF compounds by macrostructural templating on porous alumina pellets in order to obtain mechanically stable hierarchical porous catalysts (MNP@MOF/Al2O3) for the efficient methanation of CO2 in a high performance experimental fixed bed catalytic reactor.

 

Objectives:

The main objective of the present project proposal is to shape MOF compounds by macrostructural templating on porous alumina pellets in order to obtain mechanically stable hierarchical porous catalysts (MNP@MOF/Al2O3) for the efficient methanation of CO2 in a high performance experimental fixed bed catalytic reactor. The specific objectives derived from this main objective are:

O1: Preparation of structured MOF supports by macrostructural templating on porous alumina pellets, and subsequent preparation of supported metal catalysts using these hybrid MOF/Al2O3 supports.

O2: Characterization of structured MOF/Al2O3 supports and of the corresponding supported metal catalysts: structure, morphology, functionality.

O3: Design of experiments (DoE) and catalytic testing of the structured MOF based catalysts in the CO2 methanation reaction: experimental set-up, catalytic activity performance under differential and integral reaction conditions (CO2 conversion, CH4 selectivity, catalyst stability), catalyst deactivation and regeneration.

 

Results & Dissemination

Phase 1 - May - December 2018 (Activity Report 1)

The specific objective of the first phase of the project was to synthesize and characterize MOF/Al2O3 composites by macrostructural templating of MOFs on alumina pellets, and to establish the best synthesis conditions for these composites. The results obtained in this phase are summarized below:

  • The synthesis procedures for the preparation of hierarchical MIL-53/Al2O3 and MIL-101/Al2O3 composites were established. Two strategies were followed: (1) the solvothermal synthesis which leads to the formation of MOF on the outer surface of alumina pellets, and (2) the impregnation method which leads to the formation of MOF inside the pores of the alumina pellets. Using the first strategy, MIL-53/Al2O3 and MIL-101/Al2O3 composites were obtained using the same equimolar reaction mixture of CrCl3 and H2BDC. Considering the reaction conditions, and more importantly the type and surface properties of the alumina support, formation of either MIL-53 (thermodynamic product) or MIL-101 (kinetic product) is favored. Using the second strategy, MIL-101/Al2O3 (IMP) composite was obtained on the alumina pellets which under solvothermal conditions gives only MIL-53.

  • 3 types of hierarchical MOF/Al2O3 composites samples were obtained, characterized from the structural, morphological and functional point of view: MIL-53/Al2O3, MIL-101/Al2O3 by solvothermal synthesis, and MIL-101/Al2O3 (IMP) by the impregnation method. CO2-TPD investigations revealed that the synthesized MOF/Al2O3 composites have promising properties for the use as catalytic supports in the CO2 methanation process envisaged by this project, due to the good capacity to chemisorb CO2 either molecularly or dissociatively on their surface.

 

Attended conferences:

O. Grad, M. Miheţ, M.D. Lazăr, G. Blăniţă – Hierarchical MOF@Al2O3 composites – influence of synthesis conditions on the growth of benzenedicarboxylate-based MOFs on γ-Al2O3, 14th Pannonian International Symposium on Catalysis, Stary Smokovec, Slovak Republic, 03 – 07 September 2018 (poster presentation).

M. Miheţ, O. Grad, G. Blăniţă, M.D. Lazăr – MOF structuring by immobilization on γ-Al2O3 – synthesis and characterization of MOF@Al2O3 composites, 7th European Congress on Chemistry – EuCheMS, Liverpool, 26 – 30 August 2018 (poster presentation).

 

Phase 2 - January - December 2019 (Activity Report 2)

The specific objective of the second phase of the project was to synthesize and characterize Ni(10%)/MOF-Al2O3 catalysts, to investigate their catalytic performance in the methanation of CO2, corroborated with the design of experiments (DoE) by statistical methods and thermodynamic analysis of the process.

3 Ni(10%)/MOF-Al2O3 catalysts were obtained, either by the wet impregnation method (IMP) or the double solvent method (DS), followed by the reduction with sodium borohydride at ambient temperature: Ni(10%)/MIL-101-Al2O3 (IMP), Ni(10%)/MIL-101-Al2O3 (DS)and Ni(10%)/MIL-53-Al2O3 (DS).

DoE evidenced that the operating temperature is the most influential factor in the methanation process, while among the possible interactions between these factors, the one given by the reaction temperature and the reactants ratio is the most significant.

Catalytic performance in the methanation of CO2 increases in the series: Ni(10%)/MIL-53-Al2O3 (DS) < Ni(10%)/MIL-101-Al2O3 (IMP) < Ni(10%)/MIL-101-Al2O3 (DS), considering both CO2 conversion, and methane selectivity.

 

.

Attended conferences:

M. Mihet, O. Grad, G. Blanita, L. Barbu-Tudoran, M. D. Lazar Effective deposition of Ni nanoparticles on MIL-101 and MIL-101/Al2O3: catalytic performance in the methanation of CO2, 12th International Symposium of the Romanian Catalysis Society, Bucharest, Roamnia, 5-7 June, 2019 (oral presentation).

M. Mihet, O. Grad, G. Blanita, M.D. Lazar Synthesis and characterization of MIL-101 based catalysts: bulk MIL-101 and immobilized MIL-101 on γ-Al2O3 as catalytic supports, 14th European Congress on Catalysis (EuropaCat 2019), Aachen, Germany, 18-23 August, 2019 (poster presentation).

M. Mihet, O. Grad, G. Blanita, L. Barbu-Tudoran, M.D. Lazar Ni@MIL-53 and Ni@MIL-53/Al2O3 catalysts: comparative performance in the methanation of CO2, 12th International Conference on Processes in Isotopes and Molecules (PIM 2019), Cluj-Napoca, Romania, 25-27 September, 2019 (poster presentation).

O. Grad, M. Mihet, M.D. Lazar, G. Blanita Hierarchical MOF/γ-Al2O3 composites: preparation and characterization, 12th International Conference on Processes in Isotopes and Molecules (PIM 2019), Cluj-Napoca, Romania, 25-27 September, 2019 (poster presentation).

Submitted paper under review:

O. Grad, M. Mihet*, G. Blanita, M. Dan, L. Barbu-Tudoran, M.D. Lazar – MIL-101-Al2O3 as catalytic support in the methanation of CO2 – comparative study between Ni/MIL-101 and Ni/MIL-101-Al2O3 catalysts, Catalysis Today (FI = 4.888) (*corresponding author)

HomeProject TimespanProject TeamSummaryObjectivesResults