Decomposition of Hydrogen peroxide over gold and palladium as catalyst - updates

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1 Decomposition of Hydrogen peroxide over gold and palladium as catalyst - updates Katie Castroagudin Allyson Mackavage Miguel Ocampo Arpit Patel Advisors: Prof. S. Podkolzin and Prof. R. Besser

2 Contents Catalyst Preparation for Gold and Palladium Katie Experimental Set Up Update and MnO2 research Allyson Experimental results, analysis and comparison Miguel Literature Search on Gold and Palladium Arpit

3 Catalyst Preparation The catalyst that we were prepared were of concentrations:.15 wt % Au 1.5 wt % Au.15 wt % Pd 1.5 wt % Pd.15 wt % Au + Pd 1.5 wt % Au + Pd All solutions are going to be supported by silicon dioxide

4 1.5 wt% Gold 1.5 wt% Palladium 50:50 mix

5 The left is a picture of the Silicon Dioxide in tablet form and the right is the product of grinding the silicon dioxide as small as possible

6 Catalyst Preparation- Incipient Wetness Impregnation Silicon Dioxide is grinded into smaller particles 1 gram of SiO2 is spread out The solutions are added drop by drop to the surface of the SiO2 The amount was predetermined by a water experiment which determined the amount of water SiO2 could absorb

7 Catalyst Preparation- Incipient Wetness Impregnation Continued The SiO2 + solution are then dried in the oven so that the metal is absorbed into the SiO2 This creates a mixture so that the metal can act as a catalyst in the overall reaction The six catalysts will then be infused with hydrogen gas

8 Catalyst Preparation The heating up of the silicon dioxide with the metals on the surface was a slow process The oven was manually heated every hour by 5 15 degrees This was done to ensure all of the gold or palladium was absorbed into the silicon dioxide

9 The Current Setup: Heater (not yet incorporated) Foil over H2O2 to prevent decomposition Flow Meter The Newest Addition to our setup Output in ice bath

10 A Closer Look: The outputted Oxygen displaces water from this bulb Oxygen Gas moves through Flow Meter Displaced water collects here and is able to be measured

11 Experimental Runs with MnO2 Currently, we are conducting runs of Hydrogen Peroxide decomposition catalyzed by Manganese dioxide The purpose is to gauge whether our setup is working properly

12 Literature Search We conducted a thorough search of literature pertaining to Hydrogen Peroxide decomposition over MnO2 Compare our results to check accuracy

13 Experimental Plan with MnO2 Step 1. Run with constant concentration of H2O2 and temperature Determine amount of time needed for reaction data to become stable Determine if reaction rate decreases with time

14 Experimental Plan with MnO2 Step 1. Complete!! It takes about 5 minutes (depending on input flow rate) for the data to stabilize Yes, the reaction rate does decrease with time, but not very significantly

15 Experimental Plan with MnO2 Step 2. Maintain constant temperature, but vary H2O2 concentration Get baseline measurements, then randomly vary concentrations to double check data Determine conversion rate try to keep it below 10%

16 % Conversion Experimental Plan with MnO2 Step 2. In progress we have baseline data, but need to double check with random runs 14.00% Conversions Higher Concentration yields higher conversion 12.00% At 3% concentration, there is little conversion, so the data is not very representative of the actual distribution 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 0.0% 5.0% 10.0% 15.0% 20.0% 25.0% 30.0% 35.0% H2O2 Concentration All but the highest tested concentrations (30%) yielded conversions below 10%

17 Experimental Plan with MnO2 Step 3. Vary temperature, but keep concentration constant Plot data to determine activation energy (ln(rate) vs. 1/T) Vary flow rate and amount of catalyst while keeping conversion below 10%

18 Flow (ml/min) Flow (ml/min) Some Experimental Results Average values every 600s (30%, 0.1 ml/min) Series Time (s) Average values every 600s (22.5%, 0.1 ml/min) Series Time (s)

19 Flow (ml/min) Flow (ml/min) Results continued Average values every 600s (15%, 0.1 ml/min) Series Time (s) Average values every 600s (7.5%, 0.1 ml/min) Time (s) Series1

20 Flow (ml/min) Results continued Average values every 600s (3%, 0.1 ml/min) Series Time (s) From plots, at higher concentrations, data is jumpy, but at lower flow rates, it s steady Relevant data is between 1200s to 8400s

21 Flow Data Analysis Smoothing via moving average Integrating using trapezoidal rule Relevant data taken at time where system is at steady state Once average flow is determined, used ideal gas law to find moles of O 2 formed From stoichiometry, determined moles of H 2 O 2 consumed Divided by weight of catalyst to arrive at reaction rate (mol/s*g)

22 Reaction Rate (mol/s*g) Reaction Rate vs. Concentration (using flow rate) Reaction Rate vs. Concentration (Using Flow Data) Series Concentration (mol%) Points below 5% concentration are suspect due to equipment accuracy. Calibration on flow meter at lowest flow rate is at 0.5 ml/min Remaining three points show linear relationship between concentration and reaction rate

23 Volume data Summary R: L-atm/mol-K Temperature: 298 K Pressure: 1 atm Duration: 8000 s Concentration H2O Displaced (L) mol H2O2 in Mol O2 Produced Mol H2O2 consumed Reaction Rate (mol H2O2/g*s) E E

24 Volume data analysis Assumed no water vapor in gas phase and pressure is at 1 atm Negligible oxygen dissolving into water (2.91 ml of 0 2 dissolved in 500ml at STP) using Henry s Law Convert O 2 volume into H 2 O 2 consumed using reaction stoichiometry Divide H 2 O 2 consumed by time and catalyst weight

25 Reaction Rate (mol/s*g) Reaction Rate vs. Concentration (using displaced volume) Reaction Rate vs. Concentration (Using Displaced Volume) Series Concentration (mol%) Shapes are almost similar As Temperature increases, the behavior of the plot becomes more pronounce.

26 Data Comparison Literature search yielded O 2 volume vs. time. For comparison, the O 2 volume from the remaining randomized set of experiments will be collected until no more oxygen is being released Literature activation energy: 47 kj/mol. Liz determined it to be around 20 kj/mol

27 H2O2 decomposition over Pd/SiO2 as a catalyst Title: Kinetics and Mechanism of Decomposition of Hydrogen Peroxide over Pd/SiO 2 Catalyst. Authors: Yury Voloshin, James Manganaro, and Adeniyi Lawal Catalyst Preparation: 2 wt % of Pd/SiO 2 prepared with sol-gel method from PdCl 2. Reactor used: Microreactor Rate measurement-h 2 O 2 titration with potassium permanganate. Testing conditions C Reaction rate: [(CH 2 O 2,in-CH 2 O 2,out)*Fliq*34(g/molH 2 O 2 )]/W

29 Reaction mechanism: Radical Mechanism of Choudhary and Samanta(reference taken by author) a) 2H 2 O 2 + 4* = 4*OH b) 4*OH = 2H 2 O + 2*O + 2* c) 2*O = O 2 + 2* Suggested by author: a) * + H 2 O 2 = *O + H 2 O b) *O + H 2 O 2 = * + H 2 O +O 2 Kinetic parameters: Ea:71 KJ/mol Rate = k 2 [H 2 O 2 ]/(1 + ([H 2 O]/K 1 [H 2 O 2 ]) (Similar to langmuir Ads.Isotherm) [O 2 ]= rate is similar in N2 and in air,[h 2 O 2 ]&[H 2 ]=order of the reaction not specified

30 Probable pathway showing involvement of protons in the synthesis of H 2 O 2 on Pd catalysts (Chanchal Samanta)

31 Rate of decomposition of H2O2 versus Concentration of H2O2

32 Decomposition of H2O2 over Pd/C in aq.h2so4 Author:Chaudhary and Gaikwad Reactor : Magnetic stirred glass reactor Catalyst:5 wt% Pd/C Testing conditions: T= K, P-95 Kpa Rate measurement: The amount of oxygen liberated was collected using pressure gas collector

35 Kinetic Results Overall Order of the reaction=1

36 Decomposition of hydrogen peroxide over gold Author: K.Gossner & H.Bishof Testing conditions:10-60 C,pH=8,Concentration range-5 to 0.005M H 2 O 2 Reaction mechanism: a) H 2 O 2 +e+* *OH+OH - b) OH - +* *OH - c) OH - +H 2 O 2 *OOH - +H 2 O d) 2*OOH - 2OH - +O 2 +2* e) *OOH - +*OH O 2 +H 2 O+2*+e Kinetic parameters: Reaction order for gold = 1 Activation energy was measured from range C. Rate=kobs*[H 2 O 2 ][H + ] -1/3

40 Future Plans 1. Complete MnO2 step 3 and ensure setup is okay 2. Begin research with Gold and Palladium Catalysts 3. Coordinate with research team in the Netherlands

Supporting Information

Supporting Information Confined space synthesis of fully alloyed AuPd nanoparticles encapsulated in porous silica Anupam Samanta, Thattarathody Rajesh and R. Nandini Devi* Catalysis and Inorganic Chemistry