Catalytic Oxidative CO2 Reforming of Methane Over Bimetallic Pd-Ni Catalyst

Ph.DDOCTOR OF PHILOSOPH

Sintesis polivinil alkohol tersulfonasi sebagai katalis dalam produksi metil ester: review

A B S T R A C TSulfonated polyvinyl alcohol (PVA) can be used as a heterogeneous catalyst in esterification or transesterification reactions during methyl ester production. This catalyst with PVA support has the potential to be used commercially like Amberlyst 46. However, there are several drawbacks in the conventional methods to produce sulfonated PVA compared to Amberlyst 46. In this paper, various processes of sulfonated PVA synthesis will be discussed including the advantages and disadvantages compared to Amberlyst 46. The synthesis of sulfonated PVA catalysts can be carried out using sulfosuccinate acid reagents or other acid reagents that have sulfonic groups that act as the active sites of the catalysts. The use of sulfosuccinate acid as the reagent produces catalysts with better catalytic activity, but the resulting product is not in granule form like Amberlyst 46 and can only be used continuously for seven times. The use of chlorosulfonic acid as the reagent resulted in granular catalysts. However, the catalyst has less catalytic activity and stability, and the reagent has a relatively high environmental impact. For the synthesis performed using sulfuric acid as the reagent, no result regarding catalytic activity has been reported elsewhere. The blending of the catalyst with other polymers resulted in improvements in the thermal stability and mechanical strength of the sulfonated polyvinyl alcohol. After a careful review of the procedures, we propose blending or double cross-linking processes combined with sulfonated PVA synthesis as a promising method to increase the thermal stability and mechanical strength of the catalysts. However, it is necessary to perform further laboratory validations on the catalytic activity of the catalysts produced from the combined method because blending may reduce the acid capacity of the catalyst.Keywords: esterification catalyst, polyvinyl alcohol, sulfonation A B S T R A KPolivinil alkohol (PVA) tersulfonasi dapat digunakan sebagai katalis heterogen dalam reaksi esterifikasi atau transesterifikasi dalam produksi metil ester. Katalis dengan support polivinil alkohol ini berpotensi untuk digunakan secara komersial seperti Amberlyst 46. Akan tetapi, PVA tersulfonasi yang disintesis secara konvensional masih memiliki banyak kekurangan dibandingkan dengan Amberlyst 46. Pada kajian ini akan dibahas mengenai berbagai alternatif proses sintesis PVA tersulfonasi termasuk kelebihan dan kekurangannya jika dibandingkan dengan Amberlyst 46. Sintesis katalis PVA tersulfonasi dapat dilakukan menggunakan reagen asam sulfosuksinat (SSA) maupun reagen asam lainnya yang memiliki gugus sulfonat yang berperan sebagai situs aktif katalis. Penggunaan reagen SSA menghasilkan katalis dengan aktivitas katalitik yang baik namun produk yang dihasilkan tidak berbentuk granula seperti Amberlyst 46 dan hanya dapat digunakan ulang sebanyak tujuh kali. Penggunaan reagen asam klorosulfonat dapat menghasilkan katalis berbentuk granula, namun memiliki aktivitas katalitik dan kestabilan kurang baik, serta reagen yang digunakan cukup berbahaya. Untuk proses sintesis menggunakan reagen asam sulfat belum ada hasil mengenai aktivitas katalitik, tetapi dengan adanya blending dengan polimer lain dapat memperbaiki kestabilan termal dan kekuatan mekanik PVA tersulfonasi yang dihasilkan. Proses blending atau double cross-linking yang digabung dengan sintesis PVA tersulfonasi dapat meningkatkan kestabilan termal dan kekuatan mekanik sehingga metode gabungan ini diyakini sebagai metode yang paling potensial dilakukan untuk menghasilkan PVA tersulfonasi dengan karakteristik terbaik. Meskipun demikian, perlu dilakukan penelitian lebih lanjut disertai tahapan pengujian aktivitas katalitik pada katalis yang dihasilkan dari metode gabungan karena kemungkinan proses blending dapat mengurangi kapasitas asam pada katalis.Kata kunci: katalis esterifikasi; polivinil alkohol; sulfonas

Sintesis Katalis Asam Heterogen Berbasis Polivinil Alkohol (PVA) dan Pemanfaatannya dalam Produksi Metil Ester Asam Lemak

Sulfonated polyvinyl alcohol is a potential heterogeneous acid catalyst for fatty acid methyl esters (FAME) production. The catalyst (PVA/SSA) was synthesized via an esterification reaction between polyvinyl alcohol (PVA) and sulfosuccinic acid (SSA). This research aimed to study the effect of several process variables, such as the molecular weight (MW) of PVA, washing step with methanol, annealing conditions (time, temperature, and annealing pressure), and drying temperature on the performance of the PVA/SSA catalyst in methanol and free fatty acid (FFA) esterification. The sulfonated PVA catalyst was successfully synthesized, as indicated by the presence of the sulfonate group (SO3) at an absorption band of 1267 cm-1 and the carbonyl group (C=O) at an absorption band of 1628 cm-1 in the FT-IR spectra. The resulting PVA/SSA catalyst shows a good performance, where maximum conversion of the fatty acid esterification reaction can reach 81.9%. In addition, the catalyst can be used for at least four repetitions with a decrease in FAME conversion from the first to the second stage of 28.2% and has relatively stable performance in the second and subsequent reactions (conversion range 49, 1% - 58.8%). The resulting catalyst also has good thermal stability with a first-stage degradation range of 200oC to 290oC, allowing it to be applied in a temperature range suitable to the FAME manufacturing industries requirement

Enhancing performance of Ni/La2O3 catalyst by Sr-modification for steam reforming of toluene as model compound of biomass tar

10.1039/c4ra16983bRSC Advances52317834-1784