عنوان

Methanol conversion to light olefins over commercial zeolites

شماره

TLpq303925344

زبان متن نوشتاري يا گفتاري و مانند آن

انگلیسی

عنوان اصلي

Methanol conversion to light olefins over commercial zeolites

نام عام مواد

[Thesis]

نام نخستين پديدآور

U. A. El-Nafaty

نام ناشر، پخش کننده و غيره

King Fahd University of Petroleum and Minerals (Saudi Arabia)

تاریخ نشرو بخش و غیره

1990

نام خاص و کميت اثر

183

جزئيات پايان نامه و نوع درجه آن

M.Sc.

کسي که مدرک را اعطا کرده

King Fahd University of Petroleum and Minerals (Saudi Arabia)

امتياز متن

1990

متن يادداشت

The conversion of methanol to light olefins (MTO) over commercial narrow pore Silicoaluminophophate SAPO-34, and pentasil type ZSM-5 and Silicalite S-115, was studied in a fixed bed tubular reation system. Nitrogen was used as carrier gas. Experiments were caried out at various temperatures, space velocities (WHSV) and methanol-to-nitrogen (wt) ratio to study their effects on catalyst activity, selectivity, product distribution and coke deposition. ZSM-5 and S-115 were modified by impregnation with various metal elements to investigate their effects on catalyst active life time and selectivity to lower olefins. At 400C and 4 hr WHSV SAPO-34 exhibited higher initial selectivity to lower olefins than both ZSM-5 and S-115 but also deactivated more rapidly (< 2hrs). This was attributed to the catalyst's narrow pore size which enhanced coke formtion leading to poisoning of active sites an blockade of pore channel entrances. The optimum operting conditions for S-115 and ZSM-5 were found to be 375C and 450C respectively at 4hr WHSV and 2.67 methanol-to-nitrogen (wt) ratio. S-115 showed higher overall selectivity to olefins than ZSM-5 at optimum conditions. Active life-on-stream was also longer for S-115 than ZSM-5 with 58.1 and 25.5 hr respectively. Since both zeolites have identical pore-sizes and strucutres, the better performance of S-115 was attributed to its higher silica/alumina ratio of 300 as compared to ZSM-5 which had a silica/alumina ratio of 40. Modification of the two zeolites with various elements showed the degree of selectivity to light olefins to vary according to the modifying element. With S-115, the selectivity was found to vary according to the order usd\rm Ba>La>Ag>Cu>Ca>Sr>Ga>Cd>In,usd while for ZSM-5, the selectivity decreased in the order usd\rm In>Ag>Cu>Cd.usd Optimum Ba-loading on S-115 for high olefin yield was found to be 5.2% by impregnation and 0.03% by ion-exchange.

موضوع مستند نشده

Applied sciences

موضوع مستند نشده

Chemical engineering

مستند نام اشخاص تاييد نشده

U. A. El-Nafaty

نام الکترونيکي

فرمت انتشار

p

نوع ماده

[Thesis]

کد کاربرگه

276903

سطح دسترسي

a

تكميل شده

Y