ICCF-17, 12-17August, 2012, @ Daejeon Korea 1/25 Isotope Effect for Heat Generation upon Pressurizing Nano-Pd/Silica Systems with Hydrogen Isotope Gases T.Hioki, N.Sugimoto, T.Nishi, A.Itoh and T.Motohiro Toyota Central R & D Labs., Inc., Japan
2/25 Outline1. Background (1) Motivation: Arata and Zhang’s experiment (2) Our previous replication experiments (3) Why silica matrices2. Results of heat measurements for nano-Pd/Silica’s3. Summary and Next Step
6/25Summary of Our Previous Results1. Marked difference in the heat generationbetween the loadings with D2 and H2 was notobserved for the samples studied: ・Pd nanopowder (Tanaka AY4030), ・20wt%Pd-Al2O3 ・30wt%Pd-ZrO2(Santoku)2. D/Pd or H/Pd was rather smaller than that of Pdbulk： < 0.7 ----- Why ? ----- ＜Possible Reason＞ We did not observe the property of nano-Pd, although the initial size of Pd was < 10nm Nano-Pd becomes bigger once it is exposed to hydrogen
9/25How to suppress the growth of Pd?If Pd particles are inside the pores of porous matrices, the growth of Pd may be considerably suppressed. Zeolite ～1nm
10/25 FSM ( pore size > 1.5nm) ( Folded Sheets Mesoporous Material )micelle S. Inagaki, Y.Fukushima and K.Kuroda: J. Chem. Soc., Chem. Commun. 8, 680 (1993)Structure Model of FSM Precursor TEM Image of FSM-16 MCM ( Mobil Crystalline Material) C.T. Kresge et al., Nature 359, 710 (1992)
11/25 Structure of FSM: ３TypesSi/Surf.=1/0.1 Si/Surf.=1/0.16 50nm 50nm 50nm ３０ｎｍ 1.5-2nm 2D-Hexagonal Cubic 3D-Hexagonal （P6mm) （Pm3n) （P6３/mmc) A-Type B-Type C-type TOYOTA CRDL, INC.
Calorimetry 13/25 Ｍｅｔｈｏｄ Ｄａｔａ Ｅｘａｍｐｌｅ Evacuation, Gas supply 5wt%Pd/Zeolite, 4thD2 33.6 1.2 filter 33.5 Tin 1 Temperature (℃） D2 Pressure （MPa) 33.4 33.3 Tout 0.8 Inlet Water 33.2 Temperature 0.6 33.1 33 0.4 Powder Sample 32.9Tout Water Pipe 0.2 Tin 32.8 32.7 0Outlet Water 0 50 100 150 Sample VesselTemperature Time (min) Schematic of the Calorimeter Tin, Tout, Gas Pressure vs Time
14/25Procedure of Heat Measurement Vacuum Baking Synthesis @350℃ for 3hSample Vessel Pressurization from 0 to 1MPa Evacuation Depressurization for 2days from 1 to 0MPa
15/25 Heat Generation with Pressurization Heat Power & Gas Pressure vs. Time Pressure-Concentration -Temperature ( 4th Cycle Pressurization with D2 ) Relationships for Pd-H 1 1.2 1st stage 2nd stage Equilibrium Pressure (Pa) 0.8 1 Pressure (PMa) α 0.6 4th D2 0.8Pout (W) 0.4 0.6 D2 0.2 α’ 0.4 α‘ 0 0.2 α＋α’ α + α‘ α -0.2 0 0 50 100 150 Time (min) Hydrogen Concentration H/Pd
16/25Heat as a Function of Pressurization Cycle 5ｗｔ％Ｐｄ／Ｚｅｏｌｉｔｅ 6 (1) Differences in th generated heat 5 between D2 and H2 are clearly seen up to several cyclesHeat (kJ) 4 D22 D (2) The isotope effect disappears atHeat(kJ) increased number of cycles 3 2 H2 H2 1 0 1st D2 3rd H2 4th D2 5th H2 6th D2 7th H2 8th D2 9th D2 10th H2 11th H2 13th H2 15th H2 2nd D2 12th D2 14th D2 16th D2 Pressurization Cycle Ｐｒｅｓｓｕｒｉｚａｔｉｏｎ Ｃｙｃｌｅ Cycle of Measurement
17/25TEM Observation of Pd before and afterHeat Measurements (1) 5ｗｔ％Ｐｄ／Ｚｅｏｌｉｔｅ As-synthesized After 15 cycle measurements Pd seems to exist Pd precipitates on the surface in the pores of zeolite crystal grain
18/25TEM Observation of Pd before and afterHeat Measurements (2) As-synthesized After 15 cycle measurement Almost all the Pd seem to precipitate on to the surface of zeolite grain
19/25Heat as a Function of Pressurization Cycle 0.80 9.85wt%Pd / FSM 0.70 D2 D2 系列1 H2 H2 系列2 D2 average 0.53 0.53 D2 average 0.60 H2H2 average 0.41 average 0.41 0.50 Heat （ｋJ ) Heat (kJ) 0.40 0.30 0.20 0.10 0.00 Pressurization Cycle Pressurization cycle (1) The heat with D2 is clearly larger than that with H2 (～30％） (2)The isotope effect does not decrease with increasing cycle
TEM Observation of Pd before and 20/25after Heat Measurements 9.85wt%Pd / FSM As- synthesized After 15-cycle measurements Pd seems to keep staying inside the pores of FSM even after 15 cycle measurements
21/25Heat as a Function of Pressurization Cycle 1.98wt%Pd / FSM 0.35 0.3 D2 H2 0.25 Heat ( kJ ) 0.2 0.15 0.1 0.05 0 2nd 3rd 4th 5th 6th 7th 8th 9th 10th D2 H2 D2 H2 D2 H2 D2 H2 D2 Pressurization Cycle A large isotope effect is seen for lower concentration of Pd in FSM
TEM Observation of Pd after 22/25 Heat Measurements 1.98wt%Pd / FSMPrecipitation of Pd is hardly seen after the 10 cycle measurements
23/25 Heat Power & Gas Pressure vs. Time for 1.98wt%Pd/FSM Comparison of 7th H2 to 8th D2 pressurization 0.3 1.2 0.25 7th H2 2 7th H 1 Gas Pressure (MPa) Gas Pressure (MPa) 0.2 0.8Pout out (W) P (W) 0.15 8th DD2 8th 2 0.6 0.1 0.4 0.05 0.2 0 0 -0.05 -0.2 0 20 40 60 80 100 Time (min) Time (min) (1) Heat Power with D2 is clearly larger than that with H2. (2)This behavior is reproducible.
24/25 Summary1. The isotope effect for heat with pressurizationwere clearly observed for both Pd/zeolite andPd/FSM systems in a reproducible manner.2. For Pd/zeolite, it decreased with increasingcycle of pressurization and disappeared atincreased number of cycles, whereas it did notdecrease for Pd/FSM.3. For Pd/zeolite, Pd precipitates on the surface ofzeolite crystal with cycle, whereas for Pd/FSM itkeeps staying in the pores of FSM.4. Nano-sized Pd is essential for the isotope effectto be clearly observable.
25/25 Next StepWhat’s the origin of the remarkable isotope effect for heat with pressurization ?Chemical? ・・・・D-H exchange ? Quantitative determination of the heat from D-H exchange is required.Nuclear? ・・・・Reaction products ? 4He ?, n ?, γ ?