Sains Malaysiana 42(4)(2013): 515–520

Separation of Hydridocarbonyltris(triphenylphosphine) Rhodium (I) Catalyst Using

Solvent Resistant Nanofiltration Membrane

(Pemisahan Pemangkin Rodium (I) Hidridokarboniltris(trifenilfosfin) Menggunakan Membran Nanoturasan Tahan Pelarut)

Nur S. A. Razak & Hilmi Mukhtar

Chemical Engineering Department, Universiti Teknologi PETRONAS

Bandar Seri Iskandar, 31750 Tronoh, Malaysia

Maizatul S. Shaharun* & Mohd F. Taha

Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS

Bandar Seri Iskandar, 31750 Tronoh, Malaysia

Received: 24 June 2011 /Accepted: 8 March 2012

ABSTRACT

An investigation was conducted into the nanofiltration of rhodium tris(triphenyl-phosphine) [HRh(CO)(PPh3)3] catalyst used in the hydroformylation of olefins. The large size of the catalyst (>400 Da) – relative to other components of the reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (STARMEMTM 122 and STARMEMTM 240) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. The morphology of the membrane was studied by field emission scanning electron microscopy (FESEM). The solvent flux and membrane rejection of HRh(CO)(PPh3)3 was then determined for the catalyst-solvent-membrane combination in a dead-end pressure cell. Good HRh(CO)(PPh3)3 rejection (>0.93) coupled with good solvent fluxes (>72 L/m² h¹ at 2.0 MPa) were obtained in one of the systems tested. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting the solvent flux.

Keywords: Catalyst recycle; hydroformylation; membrane separation; solvent resistant nanofiltration

ABSTRAK

Penyelidikan telah dijalankan ke atas teknik nanoturasan kepada pemangkin rodium tris(trifenilfosfin) [HRh(CO)(PPh3)3] yang digunakan dalam proses penghidroformilan olefin. Saiz pemangkin yang besar (>400 Da) – berbanding dengan komponen lain dalam tindak balas memberi ruang kepada penggunaan membran yang berasaskan kepada penggunaan spesies pemangkin di samping peresapan pelarut. Keserasian pelarut-membran poliimida (STARMEMTM122 dan STARMEMTM240) telah dinilai daripada segi kestabilan membran di dalam pelarut, berserta nilai fluks pelarut bukan sifar pada 2.0 MPa. Peresapan fluks dan pengekalan pemangkin HRh(CO)(PPh3)3 menggunakan membran polyimide, telah dikaji untuk melihat kombinasi pemangkin-pelarut-membran di dalam sel tekanan tinggi. Pengekalan pemangkin [HRh(CO)(PPh3)3] yang baik (>0.93) di samping peresapan fluks pelarut yang baik (>72 L/m² h¹) diperoleh daripada salah satu sistem yang dikaji. Kesan daripada tekanan dan kepekatan pemangkin terhadap fluks pelarut dan pengekalan pemangkin telah dijalankan. Peningkatan tekanan yang ketara dapat menambah baik peresapan fluks pelarut dan juga pemangkin. Manakala peningkatan kepekatan pemangkin dapat meningkatkan pengekalan pemangkin tanpa mempengaruhi peresapan fluks pelarut.

Kata kunci: Hidroformilasi; kitar semula pemangkin; nanoturasan tahan pelarut; pemisahan menggunakan membran

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*Corresponding author; e-mail: maizats@petronas.com.my