Ceria nanoparticles : synthesis and application for plasma catalysis

Deepa choudhry Author

04/04/2021 Added

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The presentation discuss about new methodology to synthesis ceria nanoparticles and its applications

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[00:00:01.075]Hello everyone.
[00:00:02.240]This is Deepa Choudhry.
[00:00:03.420]I'm a 2nd year graduate student,
[00:00:05.060]working in Dr. Barry Cheung research group
[00:00:07.290]from the Department of Chemistry at UNL.
[00:00:09.470]The title for my presentation
[00:00:10.860]is "Ceria nanoparticles:
[00:00:12.770]synthesis and application for plasma catalysis".
[00:00:15.743]Cerium oxide is also known as Ceria
[00:00:17.584]is an oxide of the rare-earth metal cerium
[00:00:20.340]and has a cubic fluorite structure.
[00:00:22.360]It is a basic oxide and a single redox
[00:00:25.231]catalyst.Ceria unique catalytic ability
[00:00:27.594]to promote redox reaction originates
[00:00:29.906]from large-intrinsic oxygen storage and
[00:00:32.300]release capacity, which is associated
[00:00:34.580]with the formation and density of
[00:00:36.660]oxygen vacancy defects.Electrons from
[00:00:39.010]oxygen is transferred to adjacent
[00:00:41.080]Cerium ions that are reduced
[00:00:42.950]from cerium 4 plus to cerium 3 plus
[00:00:45.187]ionic states and oxygen vacancy
[00:00:47.232]is formed. The surface of cerium 3 plus
[00:00:49.640]ions on cerium catalyst have theorized
[00:00:52.070]to have potential sites, for surface catalysis
[00:00:54.650]without mentioning two important features of ceria.
[00:00:57.739]One wouldn't be able to describe the importance of ceria.First is the presence of oxygen vacancies defects.And second is a higher reducibility of cerium 4 plus state.
[00:01:06.451]There are many application of cerium.
[00:01:08.806]One of the important application
[00:01:10.870]is the use of it in Plasma catalysis.
[00:01:13.260]Why Plasma catalysis?
[00:01:16.667]Plasma catalysis allows,
[00:01:18.680]thermodynamically difficult reactions to proceed
[00:01:21.060]at ambient pressure and temperature,
[00:01:23.069]due to activation of gas molecules
[00:01:25.060]by energetic electrons created in the plasma.
[00:01:27.930]However, the plasma is very reactive but not selective,
[00:01:30.512]And thus a catalyst is needed to improve the selectivity.
[00:01:33.966]our long-term goal is to study catalytic
[00:01:37.350]plasma driven hydrogenation of CO2, towards
[00:01:40.160]methanol production and to address some
[00:01:42.700]important question that
[00:01:44.290]what is the role of oxygen vacancy on cerium surface?
[00:01:47.460]What are the reaction intermediates form?
[00:01:50.010]How plasma is coupled with cerium
[00:01:52.263]catalyst helps in methanol production?
[00:01:54.610]I would like you to discuss
[00:01:56.305]two objectives of the project.
[00:01:58.142]First objective was to synthesize ceria
[00:02:00.460]using acetate for higher yields via ozonation
[00:02:03.112]method There are many synthetic routes such as sol gel method,hydrothermal method, and microwave method been reported to produce nano ceria.
[00:02:11.540]However, they are expensive time consuming
[00:02:14.587]and require elevated temperature and pressure.
[00:02:17.610]Recent increasing uses of ceria
[00:02:19.065]and research in industrial application
[00:02:21.090]have fostered continuing development of efficient method
[00:02:23.601]to synthesize the material.
[00:02:25.725]Recently we reported the synthesis of nano particles.
[00:02:29.190]with two to five nanometer diameters,
[00:02:31.630]by directly bubbling ozone to alcoholic solution
[00:02:33.991]of cerium salts with the reaction yield
[00:02:36.630]10%, our research demonstrated that
[00:02:39.262]this methods reaction yield could be increased to over 90%
[00:02:43.862]by controlling the acidity of the reaction mixture
[00:02:47.046]with Lithium acetate with the direct ozonation method.`
[00:02:52.021]Our second objective is to investigate the effect
[00:02:54.930]of doped ceria on methanol production.
[00:02:57.280]The chemical conversion
[00:02:58.380]and utilization of CO2 is a promising step
[00:03:00.610]for the recycling of carbon resource.
[00:03:02.990]In recent studies , CO2 hydrogenation
[00:03:04.930]to methanol has gained considerable attention.
[00:03:08.400]Despite a well-developed process for
[00:03:09.940]CO2 hydrogenation to methanol the use of CO2 gas
[00:03:13.430]as a feed stock remains a challenge
[00:03:15.860]as CO2 is kinetically and thermodynamically inert and
[00:03:17.584]requires
[00:03:19.067]high temperature and pressure.
[00:03:22.340]For addressing this difficulty
[00:03:24.120]our aim is to design a plasma reactor
[00:03:26.470]and study the effect of doped ceria
[00:03:28.270]towards, methanol production.
[00:03:30.190]A non thermal plasma Catalytic synthesis
[00:03:32.600]is emerging as an efficient alternative
[00:03:34.910]to the conventional methanol synthesis.
[00:03:36.560]Since it can be used at atmospheric pressure
[00:03:39.420]at room temperature,Briefly I will discuss the method
[00:03:43.690]we used to synthesize nano ceria.
[00:03:45.912]A gas mixture of oxygen and ozone,
[00:03:48.590]was bubbled through the reaction mixture of
[00:03:50.300]cerium nitrate, Lithium acetate and Ethanol
[00:03:52.610]for 30 minutes to yield ceria nano particles
[00:03:55.350]the orange-red precipitated suspension was
[00:03:57.920]centrifuged for 20 minutes,
[00:03:59.570]the precipitate was resuspended
[00:04:01.220]in ethanol and recentrifuged
[00:04:03.500]The step was repeated with nano pure water.
[00:04:06.200]and recentrifuged. The resulting orange red precipitates
[00:04:10.220]was vacuum dried for five hours and dried overnight.
[00:04:13.340]The effect of increasing lithium acetate to cerium
[00:04:15.620]nitrate ratio was explored to demonstrate the relationship
[00:04:20.140]between product- yield, acetate concentration
[00:04:22.661]crystallinity and size distribution of nano particles.
[00:04:26.370]Average size of particle was observed to decrease.
[00:04:30.270]While crystallinity increase.
[00:04:32.230]By increasing the mol ratio of lithium acetate
[00:04:34.420]to cerium nitrate.
[00:04:36.720]In reaction mixture, we successfully increased
[00:04:39.280]the yield of ceria nano particles in 30 minutes
[00:04:41.963]from 10% to 90% by cerium content
[00:04:46.810]ceria can be doped with many transition elements.
[00:04:49.210]Since the ionic radius of these dopants is comparable.
[00:04:52.160]to cerium 3 plus and cerium 4 plus ionic states
[00:04:55.640]ceria based catalysts have been found
[00:04:57.510]to possesses higher activity and selectivity.
[00:05:00.800]This slide summarizing our collaborators simulation results
[00:05:04.750]for CO2 conversion to methanol for doped ceria
[00:05:08.040]where M is nickel, copper and ruthenium.
[00:05:12.204]Overall calculation suggests nickel doped ceria
[00:05:15.180]as the most promising system.
[00:05:17.220]As in case of nickel, the energy required
[00:05:20.889]for the formation of intermediate
[00:05:22.780]of H3CO is lower as compared to copper and ruthenium.
[00:05:27.494]Why methanol, The chemical conversion
[00:05:30.420]and utilization of CO2 is a promising step
[00:05:32.712]for the recycling of carbon resource.
[00:05:35.060]There are many applications of methanol like liquid methanol,
[00:05:37.570]Can be used as a fuel and energy carrier
[00:05:39.730]and good for portable power.
[00:05:42.409]our plasma reactor is a typical cylindrical
[00:05:44.558]Dielectric barrier discharge reactor
[00:05:47.300]using a stainless steel as an inner electrode
[00:05:50.050]with a course quartz tube covered
[00:05:51.780]with aluminum tape as an outer
[00:05:54.443]electrode
[00:05:55.276]DBD is one of the popular method to generate non-thermal plasma
[00:05:57.810]which is made of high-energy electrons and free radicals.
[00:06:01.207]And chemically active species.
[00:06:02.690]So it has a property being prone to, chemical reaction.
[00:06:05.850]The discharge length of DBD is 90 millimeter
[00:06:08.640]with a discharge gap of one millimeter
[00:06:11.000]Required gases will flow through this discharge gap.
[00:06:14.770]With the generation of plasma through high voltage supply instrument.
[00:06:18.100]The inner electrode is connected to a high volatge supply
[00:06:21.323]with a peak volatge of 10,000 volts.
[00:06:24.155]at a fixed frequency of 15 kilohertz.
[00:06:26.580]The outer electrode is grounded through a capacitor.
[00:06:29.700]Mixture of gasses controlled
[00:06:31.230]with a mass flow, controller will flow into a DBD reactor.
[00:06:35.243]A high voltage probe is used to measure the applied voltage
[00:06:38.797]and charge volatge
[00:06:39.920]signals will be recorded with an Oscilloscope.
[00:06:42.657]The discharge power will be calculated using Q-V lissajous plots
[00:06:47.630]The product analysis will be done utilizing gas
[00:06:50.500]chromatographic equipped with a capillary column
[00:06:53.460]and a mass spectrometer detector
[00:06:55.520]In the unique plasma process,
[00:06:57.200]The mass spectra shown here reveals the presence of Methane
[00:07:01.743]and methanol with 30 SCCM of H2
[00:07:08.186]and 10 SCCM flow rate of CO2,
[00:07:10.640]This process can be further
[00:07:12.010]explored using ceria catalyst.
[00:07:13.620]Based on its unique catalytic ability,
[00:07:15.960]discussed at the starting of the talk
[00:07:19.050]I will wrap up the presentation
[00:07:20.390]with some conclusions,
[00:07:21.650]which are, Cerium oxide nano particles
[00:07:23.970]have been successfully synthesized
[00:07:25.360]and characterized. The synthesis efficiency and crystallinity
[00:07:28.303]has increased by the addition of lithium acetate
[00:07:30.684]via ozone-mediated routes close to a hundred percent.
[00:07:34.847]Methanol can be produced via hydrogenation
[00:07:37.284]of CO2 using plasma at atmospheric pressure
[00:07:39.797]and room temperature.
[00:07:41.290]Lastly, I would like to thank National Center
[00:07:43.730]for Energy Science Research for this great opportunity.
[00:07:46.692]I would also like to thank my advisor
[00:07:48.852]my group members and others for their help
[00:07:51.142]and guidance. Thank you.

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Ceria nanoparticles : synthesis and application for plasma catalysis

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