Removal of hydrogen sulfide from biogas using ceo2 naoh psac synthesis and performance from laboratory scale to scale up process design / Lau Lee Chung
Dalam penyelidikan ini, bahan serap CeO2/NaOH/PSAC telah berjaya
dihasilkan dan digunakan dalam penyingkiran hidrogen sulfida dari biogas.
Penyelidikan awal menunjukkan laluan penghasilan terbaik adalah menggunakan
kaedah rendaman untuk impregnasikan serium oksida dan natrium hidroksida ke
karbon teraktif tempurung kelapa sawit (PSAC). Di samping itu, proses pengkalsinan
mesti dilakukan sebagai langkah penyediaan terakhir kerana proses ini meningkatkan
kapasiti serapan. Parameter penyediaan yang dikaji ialah masa impregnasi (0 – 180
minit), jumlah serium (1 – 10% wt serium), kepekatan natrium hidroksida (0.2 –
1.0M NaOH), suhu (250 – 500oC) dan tempoh pengkalsinan(1 – 4 jam).
Pengoptimuman parameter penyediaan bahan serap telah dilakukan dengan nilai
optimum ialah 1.5 jam masa impregnasi, 5 wt% serium, 1.0 M NaOH, 400oC suhu
pengkalsinan dan 3 jam masa pengkalsinan. Parameter operasi yang mempengaruhi
kapasiti serapan ialah suhu serapan, kepekatan H2S, jumlah bahan serap dan kadar
aliran. Nilai maksimum kapasiti serapan boleh dikenalpasti untuk setiap parameter
operasi. Selain itu, komponen gas lain seperti air, karbon dioksida dan metana juga
boleh mempengaruhi kapasiti serapan dengan berbeza. Analisa data menunjukkan
isoterma serapan Freundlich paling sesuai untuk menggambarkan tingkah laku
serapan. Penyelidikan termodinamik menunjukkan perubahan entalpi (ΔH) dan
perubahan entropi (ΔS) dikirakan sebagai –6.0 kJ/mol dan 25.7 J/mol.K. Serapan
adalah pseudo peringkat kedua dengan tenaga pengaktifan 11.7 kJ/mold dan kadar
tetap adalah antara 2.387–4.066 X 10-6 g/mg.min untuk suhu 30–70oC. Lengkung
bulus disesuaikan dengan bagus dengan menggunakan model lengkung bulus yang
dibangunkan oleh Chu (2004). Sehingga 78% kapasiti serapan asal dapat dicapai
dalam penyelidikan penjanaan semula dengan mengunakan rawatan haba di bawah
atmosphere lengai. Suhu dan masa penjanaan semula adalah 500oC dan 4 jam masing
masing. Skala naik proses serapan dengan bahan serapan CeO2/NaOH/PSAC telah
berjaya direkabentuk dengan kadar pulangan (ROR) selama dua tahun. Penyelidikan
simulasi juga dijalankan dan didapati kenaikan kecekapan berlaku pada kadar aliran
yang lebih tinggi dan kolom serapan yang lebih kecil.
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In this study, CeO2/NaOH/PSAC sorbent was successfully synthesized and
applied in hydrogen sulfide removal from biogas. Preliminary study showed that the
best synthesis route was using soaking method to impregnate cerium oxide and
sodium hydroxide onto palm shell activated carbon (PSAC). In addition, calcination
must be applied as final step of the preparation because it increased the sorption
capacity. Preparation parameters studied were impregnation time (0 – 180 min),
cerium amount (1 – 10% wt Ce), sodium hydroxide concentration (0.2 – 1.0M
NaOH), calcination temperature (250 – 500oC) and duration (1 – 4 hours).
Optimization of sorbent preparation parameters was successful and the optimum
values were 1.5 hours impregnation time, 5 wt% cerium, 1.0 M NaOH, 400oC
calcination temperature and 3 hours of calcination time. Operating parameters that
were found to affect the sorption capacity were sorption temperature, H2S
concentration, sorbent amount, and flow rate. Maximum value of sorption capacity
can be identified for each of these operating parameters. Moreover, other gas
components such as water, carbon dioxide and methane can also affect the sorption
capacity differently. Data analysis showed that Freundlich sorption isotherm can best
described the sorption behavior. Thermodynamic study showed that enthalpy change
(ΔH) and entropy change (ΔS) were calculated to be –6.0 kJ/mol and 25.7 J/mol.K.
The sorption was pseudo–second order with activation energy 11.7 kJ/mol and rate
constant was between 2.387–4.066 X 10-6 g/mg.min for temperature 30–70oC.
Breakthrough curve was fitted well by using breakthrough model developed by Chu
(2004). Up to 78% of original sorption capacity was achieved in the regeneration
study using heat treatment under inert atmosphere. The regeneration temperature and
time were 500oC and 4 hours, respectively. Scale up sorption process using the
developed CeO2/NaOH/PSAC sorbent was successfully designed with a rate of
return (ROR) of two years. Simulation study was also performed and increased
efficiency at higher flow rate and smaller sorption column was discovered.
Removal of hydrogen sulfide from biogas using ceo2 naoh psac synthesis and performance from laboratory scale to scale up process design / Lau Lee Chung
Removal of hydrogen sulfide from biogas using ceo2 naoh psac synthesis and performance from laboratory scale to scale up process design_Lau Lee Chung_K4_2015_MYMY