1. A method of making light olefins, comprising:
contacting an oxygenate feed with a first zeolite catalyst comprising a ZSM-5 molecular sieve in a first bed or reactor to form a first product; and
contacting at least a portion of the first product with a second zeolite catalyst comprising a zeolite molecular sieve selected from the group consisting of ZSM-22, ZSM-23, ZSM-35, ZSM-48, and mixtures thereof in a second bed or reactor separate from the first bed or reactor to form a second product wherein, the first and second zeolite catalysts are in separate beds or reactors.
2. The method of claim 1, wherein the oxygenate feed contains at least 70 wt. % oxygenate.
3. The method of claim 2, wherein the oxygenate feed contains at least 80 wt. % oxygenate.
4. The method of claim 3, wherein the oxygenate feed contains at least 90 wt. % oxygenate.
5. The method of claim 1, wherein the ZSM-5 molecular sieve is selected from the group consisting of an unmodified ZSM-5, a phosphorous modified ZSM-5, a steam modified ZSM-5 having a micropore volume reduced to not less than 50% of that of the tmsteamed ZSM-5, and mixtures thereof.
6. The method of claim 1, wherein the second zeolite catalyst comprises a zeolite molecular sieve selected from the group consisting of ZSM-22, ZSM-35, and mixtures thereof.
7. The method of claim 1, wherein the oxygenate feed is contacted in a first bed containing the first catalyst and the first product is contacted in a second bed containing the second zeolite catalyst.
8. The method of claim 1, wherein the oxygenate comprises methanol and the second product comprises the light olefins.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A pipe assembly that includes first and second pipe sections (12, 14) connected in series along a pipeline axis (16), said pipe sections having pipe ends (20, 22) with each pipe end having a pair of axially and radially-facing abutments (30, 34 and 32, 36, 66, 67 and 68, 69) wherein one abutment of each pipe section is engaged with an abutment of another pipe section, and each pipe end has a thread (24, 26) engaged with the thread of the other pipe section wherein said threads each lies between a pair of abutments, and wherein there are a pair of spaces (50, 52) between said pipe sections with each space lying between an end of said thread and an abutment of the same pipe section, wherein:
the axial length (L) of each of said threads is less than 60% of the distance (M) between two axially-facing abutments (30, 32) of the same pipe section.
2. The pipe assembly described in claim 1 wherein:
the axial length (L) of each of said threads is less than 50% of the axial distance (M) between the two abutments of the same pipe section.
3. The pipe assembly described in claim 1 wherein:
the axial length (E, F) of each space (50, 52) is at least 25% of the distance (M) between two axially-facing abutments of the same pipe section.
4. The pipe assembly described in claim 1 wherein:
a first of said pipe ends (12) forms a nib (40A) lying beside one of said abutments (36), and a second of said pipe ends (14) forms a groove (42) lying beside one of its abutments (32);
said first pipe section has a guide surface (69) that extends primarily axially and has a radially inclined surface part (75) that is inclined from an axial direction to deflect the nib into close alignment with the groove.
5. A pipe assembly which includes first and second pipe sections having pipe ends (20, 22) connected together at a pipe connection (51), with a first connection end (53) where said first pipe section has a radially outer pipe part (92) of a thickness R and an inner pipe part (90) of a greater thickness T, wherein:
at said pipe first connection end (53) said outer pipe end has a nib (40A) and said inner pipe end has a groove (42) for receiving said nib in an interference fit as said pipe ends move together along a pipe assembly axis (16) during a connection;
said inner pipe end has at least one inclined wall (72, 75) positioned to deflect said nib radially outward into alignment with said groove as said pipe section ends are moved together along said axis during a connection.
6. The pipe assembly described in claim 5 wherein:
said pipe connection (51) has a second connection end (55) where said outer pipe end (20) is of greater thickness than said inner pipe end (22);
at said pipe second connection end said inner pipe end (22) has a nib (40B) and said outer pipe end has a groove (40) for receiving said nib in an interference fit, and said outer pipe end forms an inclined wall (72, 75) that is positioned to deflect said nib radially inward into alignment with said groove of said outer pipe end.
7. The pipe assembly described In claim 5 wherein:
said pipe connection has a second connection end (55) where said outer pipe end (20) is of greater thickness than said inner pipe end;
said pipe connection has tapered threads (24, 26) that join said pipe ends along a distance (L), and said pipe connection has spaces of length E, F between each end of the threads and said connection ends;
said spaces of lengths E, F are each more than 25% of the total length (M) of said distance L plus said lengths E plus F.
8. A pipe assembly that Includes first and second pipe sections (12, 14) connected in series along a pipeline axis (16) by a connection (51) that has opposite connection ends (53, 55) at which said pipe sections have axially-facing adjacent abutments (30, 34 and 32, 36), and with each pipe end having a thread (24, 26) engaged with the thread of the other pipe section along an axial length L and wherein the pipe sections form spaces (50, 52) of lengths E and F on either side of the threads between ends of said threads and corresponding ends (53, 55) of said connection, wherein:
said distances E and F are each at least 25% of the distance M between the axial abutments (32, 36 and 30, 34) of each pipe section.
9. A pipe assembly that includes first and second pipe sections extending along a pipe axis (16) and having pipe ends, including a first pipe end (20) that surrounds a second pipe end (22), and wherein said second pipe end has a first axially-extending groove (42) and said first pipe end has a first nib (40A) that prefects axially into said groove, wherein said groove is spaced a distance R from a radially outer surface (14a) of said second pipe end (20), and said groove is spaced a distance T from the radially inner surface of said first pipe end, where said distance T Is greater than said distance R; wherein:
said first and second pipe ends have inclined walls (72, 73, 75) that are constructed to deflect said nib radially outward into alignment with said groove when said pipe sections are moved together during assembly of said pipe assembly, whereby to minimize strain in said pipe sections.
10. The pipe assembly described in claim 9 wherein:
said first groove has a radially outer groove wall (82) which has been radially deflected by less than half the radially outward deflection of said nib produced by said inclined walls (72, 73, 75).