Preparation of Ru/Rh Bimetallic Nanoparticles Stabilized by Heterocyclic Poly(propylene imine) Dendrimer and Their Application for Catalytic Hydrogenation of Nitrile-Butadiene Rubber†

doi:10.7503/cjcu20150797

Abstract

Abstract:

A series of Ru/Rh bimetallicdendrimer-stabilized nanoparticles[Gn-M(Ru_xRh_100-_x) DTNs, x: mole molar fraction of Ru] was prepared by complexing-reducing method with the 15-membered azamacrocycles-terminated poly(propylene imine) dendrimer(Gn-M, n=2, 3, 4) as template. These bimetallic DTNs were used as catalysts for the hydrogenation of nitrile-butadiene rubber(NBR). The results of UV-Vis spectroscopy(UV-Vis), X-ray diffraction(XRD) and energy dispersive spectrum(EDS) indicated that bimetallic ions were successful reduced and stabilized by Gn-M. Particle size analysis showed that the average size of G2-M(Ru₅₀Rh₅₀), G3-M(Ru₅₀Rh₅₀) and G4-M(Ru₅₀Rh₅₀) DTNs were 7.5, 8.1 and 4.5 nm, respectively. G4-M(Ru₃₀Rh₇₀) DTNs catalyst reached the maximum hydrogenation degree(HD) of 99.51%, and the results of gel fraction measurement and ¹H nuclear magnetic resonance(¹H NMR) indicated that Ru/Rh DTNs were highly selective for the catalytic hydrogenation of NBR. Moreover, the HD can still reach 90.58% after twice recycle.

Key words: Heterocycle, Poly(propylene imine) dendrimer, Ru/Rh bimetallic nanoparticles, Nitrile-butadiene rubber, Hydrogenation

CLC Number:

O631
O643.36

TrendMD:

XIAO Ye, WANG Yang, ZHOU Wei, PENG Xiaohong. Preparation of Ru/Rh Bimetallic Nanoparticles Stabilized by Heterocyclic Poly(propylene imine) Dendrimer and Their Application for Catalytic Hydrogenation of Nitrile-Butadiene Rubber^†[J]. Chem. J. Chinese Universities, 2016, 37(4): 786.

Figures/Tables 9

Fig.1 UV-Vis spectra of G2-M(A), G3-M(B) and G4-M(C) bimetallic nanoparticles with various Ru/Rh molar ratios^(A) a. G2-M; b. G2-M(Ru); c. G2-M(Ru70Rh30); d. G2-M(Ru50Rh50); e. G2-M(Ru30Rh70); f. G2-M(Rh). (B) a. G3-M; b. G3-M(Ru); c. G3-M(Ru70Rh30); d. G3-M(Ru50Rh50); e. G3-M(Ru30Rh70); f. G3-M(Rh). (C) a. G4-M; b. G4-M(Ru); c. G4-M(Ru70Rh30); d. G4-M(Ru50Rh50); e. G4-M(Ru30Rh70); f. G4-M(Rh).

Fig.2 High-resolution TEM images(A—C) and the corresponding size distribution histograms(A'—C') of G2-M(Ru50Rh50)(A, A'), G3-M(Ru50Rh50)(B, B') and G4-M(Ru50Rh50)(C, C') nanoparticles

Table 1 Comparison of the calculated value and the measured value of Gn-M(Ru50Rh50) bimetallic DTNs size

Gn-M(R $u 5 0$ R $h 5 0$ DTNs)	10^-3 Atom number	d_calculated/nm	d_Measured/nm
G2-M	8.20	6.4	7.5±0.8
G3-M	10.32	6.9	8.1±1.1
G4-M	1.77	3.6	4.5±1.5

Table 1 Comparison of the calculated value and the measured value of Gn-M(Ru50Rh50) bimetallic DTNs size

Gn-M(R $u 5 0$ R $h 5 0$ DTNs)	10^-3 Atom number	d_calculated/nm	d_Measured/nm
G2-M	8.20	6.4	7.5±0.8
G3-M	10.32	6.9	8.1±1.1
G4-M	1.77	3.6	4.5±1.5

Fig.3 EDS analysis for G4-M(Ru50Rh50) bimetallic nanoparticles

Fig.4 XRD patterns of G4-M(Rh)(a), G4-M(Ru30Rh70)(b), G4-M(Ru50Rh50)(c), G4-M(Ru70Rh30)(d) and G4-M(Ru)(e) DTNs

Fig.5 Hydrogenation degree(HD) of NBR as various molar ratio of rhodium in G2-M(RuxRh100-x)(a), G3-M(RuxRh100-x)(b) and G4-M(RuxRh100-x)(c) bimetallic nanoparticles^Conditions: NBR 3.6 g, mDTNs/mNBR=0.35%, mDTNs/mTPP=10%, 800 r/min of agitation, 100 ℃, 5.5 MPa of H2, reaction time: 9 h.

Fig.6 1H NMR spectra of NBR(A) and HNBR(B)^ Conditions: NBR 3.6 g, mDTNs/mNBR=0.35%, mDTNs/mTPP=10%, 800 r/min of agitation, 100 ℃, 5.5 MPa of H2, reaction time: 9 h.

Fig.7 Representative FTIR spectra of NBR(a) and HNBR(b—d) with different extent of hydrogenation^HD(%): b. 65.85; c. 89.74; d. 99.51.

Fig.8 Hydrogenation degrees of NBR catalyzed by G4-M(Ru30Rh70) in different cycles^Conditions: NBR 3.6 g, mDTNs/mNBR=0.35%, mcatalysis/mTPP=10%, 800 r/min of agitation, 100 ℃, 5.5 MPa of H2, reaction time: 9 h.

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