Christian Ahoba-Sam
University College of Southeast Norway
Christian Ahoba-Sam is a final year PhD fellow at the University College of Southeast Norway, in Process, Energy and Automation Engineering. His research on ‘low temperature methanol synthesis’ is a part of a Research Council of Norway funded Future feed project, with focus on CO2utilization. He has a MSc in Chemistry from the University of Oslo, where he worked with the Catalysis Group. Christian’s scientific interests include inorganic material synthesis and characterization, catalytic testing, reactor design and nano chemistry.
Synthesis of Cu nanoparticles (NP) has attracted much attention over some time now due to their unique applications in optics, conduction and catalysis [1]. One such catalytic application is in producing methanol from synthetic gas (CO+H2) at 100 oC and 20 bar. Methanol yield, for example, was observed to decrease with increasing Cu NP size from 7 to 21 nm [2]. Several synthetic techniques for making NP have been explored in literature. A promising technique is the use of a Spinning Disc Reactor (SDR). SDR is a process intensification technique, which enhances production efficiency, safety and minimizes cost. Liquid introduced into the SDR forms a thin film due to centrifugal acceleration created by rotation of the disc, resulting in uniform micro-mixing which is critical in nucleation and crystal growth in precipitation reaction [3].
Our aim therefore is to study how the SDR operating parameters affect Cu nanoparticles sizes and its application in methanol synthesis. The Cu NP was obtained by borohydride reduction using aqueous Cu(NO3)2 solution in one stream and NaBH4 solution in a second stream and products collected in 2 % w/v starch solution to minimize agglomeration. Particle sizes were analysed using dynamic light scattering, XRD and TEM.
Our results show that variation of parameters such as flow ratio, flow rate, SDR rotation speed, reactants mole ratio and temperature affected Cu NP size distribution. Typically, Cu NP ranging from 3 to 100 nm were made depending on the parameter at play. For example faster SDR rotation led to narrower particle size distribution (Fig. 1) as adequate mass and heat transfer is enhanced for efficient micro mixing during both nucleation and crystal growth. Furthermore, the Cu NP were tested be active for methanol synthesis.
References
[1] M.B. Gawande, A. Goswami, F.-X.Felpin, T. Asefa, X. Huang, R. Silva, X. Zou, R. Zboril, R.S. Varma, Cu andCu-Based Nanoparticles: Synthesis and Applications in Catalysis, Chem. Rev., 116 (2016) 3722-3811.
[2]C. Ahoba-Sam, U. Olsbye, K.-J. Jens, Low temperature methanol synthesis catalyzed by copper nanoparticles, Catal. Today, (2017).
[3] S. Mohammadi,A. Harvey, K.V.K. Boodhoo, Chem. Eng. Journal, 258 (2014) 171-184.
Nanotechnology for environment and energy , Nanocatalysis & applications in the chemical industry , Nanofabrication, nanoprocesing & nanomanufacturing
